On one occasion the Blessed One was living at Rajagaha in the Bamboo Grove, the Squirrels' Sanctuary. A number of bhikkhus from the Blessed One's native land, who had spent the Rains there, went to the Blessed One, and after paying homage to him, sat down at one side. The Blessed One asked them: "Bhikkhus, who in my native land is esteemed by the bhikkhus there, by his companions in the holy life, in this way: 'Having few wishes himself, he talks to the bhikkhus on fewness of wishes; content himself, he talks to the bhikkhus on contentment; secluded himself, he talks to the bhikkhus on seclusion; aloof from society himself, he talks to the bhikkhus on aloofness from society; energetic himself, he talks to the bhikkhus on arousing energy; attained to virtue himself, he talks to the bhikkhus on the attainment of virtue; attained to concentration himself, he talks to the bhikkhus on the attainment of concentration; attained to wisdom himself, he talks to the bhikkhus on the attainment of wisdom; attained to deliverance himself, he talks to the bhikkhus on the attainment of deliverance; attained to the knowledge and vision of deliverance himself, he talks to the bhikkhus on the attainment of the knowledge and vision of deliverance; he is one who advises, informs, instructs, urges, rouses, and encourages his companions in the holy life'?"
"Venerable sir, the venerable Punna Mantaniputta is so esteemed and well respected in the Blessed One's native land by the bhikkhus there, by his companions in the holy life." On one occasion, Venerable Sariputta was seated near the Blessed One. Then it occurred to him: "It is a gain for the venerable Punna Mantaniputta, it is a great gain for him that his wise companions in the holy life praise him point by point in the Teacher's presence. Perhaps we might meet the venerable Punna Mantaniputta one day and have some conversation with him."
Then, when the Blessed One had stayed at Rajagaha as long as he wish, he set out to wander by stages to Savatthi. He eventually arrived at Savatthi and there he lived in Jeta's Grove, Anathapindika's Park. Venerable Punna Mantaniputta heard where the Blessed One was staying at Savatthi and went to see the Blessed One. After paying homage to the Blessed One, he sat down at one side and the Blessed One instructed, urged, roused, and encouraged him with talk on the Dhamma. After hearing the Dhamma from Buddha, Venerable Punna Mantaniputta delighted and rejoiced in the Blessed One's words, rose from his seat, and after paying homage to the Blessed One, keeping him on his right, he went to the Blind Men's Grove for the day's abiding.
Then a certain bhikkhu went to the Venerable Sariputta and said to him: "Friend Sariputta, the bhikkhu Purina Mantaniputta of whom you have always spoken highly has just been instructed, urged, roused, and encouraged by the Blessed One with talk on the Dhamma; after delighting and rejoicing in the Blessed One's words, he went to the Blind Men's Grove." Then the venerable Sariputta quickly picked up a mat and followed close behind the venerable Punna Mantaniputta, keeping his head in sight. Then the venerable Punna Mantaniputta entered the Blind Men's Grove and sat down for the day's abiding at the root of a tree. The venerable Sariputta also followed him. In the evening, the venerable Sariputta rose from meditation, went to the Venerable Punna Mantaniputta, and exchanged greetings with him.
When this courteous and amiable talk was finished, he sat down at one side and said to the venerable Punna Mantaniputta: "Is the holy life lived under our Blessed One, friend?" Punna: "Yes, friend." Sariputta: "But, friend, is it for the sake of purification of virtue that the holy life is lived under the Blessed One?" Punna: "No, friend." Sariputta: "Then is it for the sake of purification of mind that the holy life is lived under the Blessed One?" Punna: "No, friend." Sariputta: "Then is it for the sake of purification of view that the holy life is lived under the Blessed One?" Punna: "No, friend." Sariputta :"Then is it for the sake of purification by overcoming doubt that the holy life is lived under the Blessed One?" Punna: "No, friend." Sariputta: "Then is it for the sake of purification by knowledge and vision of what is the path and what is not the path that the holy life is lived under the Blessed One?" Punna: "No, friend." Sariputta: "Then is it for the sake of purification by knowledge and vision of the way that the holy life is lived tinder the Blessed One?" Punna: "No, friend." Sariputta: "Then is it for the sake of purification by knowledge and vision that the holy life is lived under the Blessed One?" Punna: "No, friend."
Sariputta: "Friend, when asked: 'But, friend, is it for the sake of purification of virtue, purification of the mind...purification of view....purification by overcoming doubt.. .purification by knowledge and vision of what is the path and what is not the path...purification by knowledge and vision of the way.. .purification by knowledge and vision... that the holy life is lived under the Blessed One?' you replied: 'No, friend.' For the sake of what then, friend, is the holy life lived under the Blessed One?"
Punna: "Friend, it is for the sake of final Nibbana without clinging that the holy life is lived under the Blessed One." Sariputta: "But, friend, is purification of virtue, purification of mind, purification of view, purification of overcoming doubt, purifiation by knowledge and vision of what is the path and what is not the path final, purification by knowledge and vision of the way, purification by knowledge and vision final Nibbana without clinging?" Punna: "No, friend."
Sariputta: "But, friend, is final Nibbana without clinging to be attained without these states?" Punna: "No, friend." Sariputta: "When asked: 'But, friend, is purification of virtue final nibbana without clinging?' you replied: 'No, friend.' When asked: 'Then is purification of mind...purification of view...purification by overcoming doubt...purification by knowledge and vision of what is the path and what is not the path.. .purification by knowledge and vision of the way...purification by knowledge and vision final Nibbana without clinging?' you replied: 'No, friend.' And when asked: 'But, friend, is final Nibbana without clinging to be attained without these states?' you replied: 'No, friend.' But how, friend, should the meaning of these statements be regarded?"
Punna: "Friend, if the Blessed One had described purification of virtue as final Nibbana without clinging, he would have described what is still accompanied by clinging as final Nibbana without clinging. If the Blessed One had described purification of mind...purification of view...purification by overcoming doubt.. .purification by knowledge and vision of what is the path and what is not the path...purification by knowledge and vision of the way...purification by knowledge and vision as final Nibbana without clinging, he would have described what is still accompanied by clinging as final Nibbana without clinging. And if final Nibbana without clinging were to be attained without these states, then an ordinary person would have attained final Nibbana, for an ordinary person is without these states. "
"As to that, friend, I shall give you a simile, for some wise men understand the statement by means of a simile. Suppose that King Pasenadi of Kosala while living at Savatthi had some urgent business to settle at Saketa, and between Savatthi and Saketa seven relay chariots were kept ready for him. Then King Pasenadi of Kosala, leaving Savatthi through the inner palace door, would mount the first relay chariot, and by means of the first relay chariot he would arrive at the second relay chariot; then he would dismount from the first chariot and mount the second chariot, and by means of the second chariot, he would arrive at the third chariot.. .by means of the third chariot, he would arrive at the fourth chariot.. .by means of the fourth chariot, he would arrive at the fifth chariot...by means of the fifth chariot, he would arrive at the sixth chariot. . .by means of the sixth chariot, he would arrive at the seventh chariot, and by means of the seventh chariot he would arrive at the inner palace door in Saketa. "
"Then, when he had come to the inner palace door, his friends and acquaintances, his kinsmen and relatives, would ask him: 'Sire, did you come from Savatthl to the inner palace door in Saketa by means of this relay chariot?' How then should King Pasenadi of Kosala answer in order to answer correctly?" "In order to answer correctly, he should answer thus: 'Here, while living at Savatthi I had some urgent business to settle at Saketa, and between Savatthi and Saketa seven relay chariots were kept ready for me. Then, leaving Savatthi through the inner palace door, I mounted the first relay chariot, and by means of the first relay chariot I arrived at the second relay chariot; then I dismounted from the first chariot and mounted the second chariot, and by means of the second chariot I arrived at the third...fourth...fifth...sixth...seventh chariot, and by means of the seventh chariot I arrived at the inner palace door in Saketa.' In order to answer correctly he should answer thus."
"So too, friend, purification of virtue is for the sake of reaching purification of mind; purification of mind is for the sake of reaching purification of view; purification of view is for the sake of reaching purification by overcoming doubt; purification by overcoming doubt is for the sake of reaching purification by knowledge and vision of what is the path and what is not the path; purification by knowledge and vision of what is the path and what is not the path is for the sake of reaching purification by knowledge and vision of the way; purification by knowledge and vision of the way is for the sake of reaching purification by knowledge and vision; purification by knowledge and vision is for the sake of reaching final Nibbana without clinging. It is for the sake of final Nibbana without clinging that the holy life is lived under the Blessed One." (one precedes another)
When this was said, Venerable Sariputta asked the venerable Punna Mantaniputta: "What is your name, and how do your companions in the holy life know you as?" Venerable Punna replied: "My name is Punna, friend, and my companions in the holy life know me as Mantaniputta." Venerable Sariputta: "It is wonderful, friend, it is marvellous! Each profound question has been answered, point by point, by the venerable Punna Mantaniputta as a learned disciple who understands the Teacher's Dispensation correctly. It is a gain for his companions in the holy life, it is a great gain for them that they have the opportunity to see and honor the venerable Punna Mantaniputta. Even if it were by carrying the venerable Punna Mantaniputta about on a cushion on their heads that his companions in the holy life would get the opportunity to see and honor him, it would be a gain for them, a great gain for them. And it is a gain for us, a great gain for us that we have the opportunity to see and honor the venerable Punna Mantaniputta."
When this was said, venerable Punna Mantaniputta asked the venerable Sariputta: "What is your name, and how do your companions in the holy life know the venerable one?" Sariputta replied: "My name is Upatissa, friend, and my companions in the holy life know me as Sariputta." Punna: "Indeed, friend, we did not know that we were talking with the venerable Sariputta, the disciple who is like the Teacher himself. If we had known that this was the venerable Sariputta, we should not have said so much. It is wonderful, friend, it is marvellous! Each profound question has been posed, point by point, by the venerable Sariputta as a learned disciple who understands the Teacher's Dispensation correctly. It is a gain for his companions in the holy life, it is a great gain for them that they have the opportunity to see and honor the venerable Sariputta. Even if it were by carrying the venerable Sariputta about on a cushion on their heads that his companions in the holy life would get the opportunity to see and honor him, it would be a gain for them, a great gain for them. And it is a gain for us, a great gain for us that we have the opportunity to see and honor the venerable Sariputta." (the two highly regarded venerable praise each other)
Thus it was that these two great beings rejoiced in each other's good words.
In summary, this discourse is a question and answer session between Venerable Sariputta (chief disciple of Buddha) and Venerable Punna Mantaniputta who was a highly regarded venerable from Buddha's native land. This discourse is named Rathavinita sutta (relay of chariots) because Venerable Punna Mantaniputta use the simile of how King Pasenadi use a relay of 7 chariots to reach Saketa from Savatthi to illustrate the path in terms of 7 purifications. Purification of virtue is for the sake of reaching purification of mind; purification of mind is for the sake of reaching purification of view; purification of view is for the sake of reaching purification by overcoming doubt; purification by overcoming doubt is for the sake of reaching purification by knowledge and vision of what is the path and what is not the path; purification by knowledge and vision of what is the path and what is not the path is for the sake of reaching purification by knowledge and vision of the way; purification by knowledge and vision of the way is for the sake of reaching purification by knowledge and vision; purification by knowledge and vision is for the sake of reaching final Nibbana without clinging. It is for the sake of final Nibbana without clinging that the holy life is lived under the Blessed One.
References: 1. www.accesstoinsight.org 2. https://suttacentral.net/ 3. The middle length discourses of the Buddha (Bhikkhu Bodhi)