On one occasion the Blessed One was living at Rajagaha in the Bamboo Grove, the Squirrels' Sanctuary. Now on that occasion the venerable Sariputta, the venerable Maha Cunda, and the venerable Channa were living on the mountain Vulture Peak. On that occasion the venerable Channa was afflicted, suffering, and gravely ill.
In the evening, venerable Sariputta rose from meditation, went to the venerable Maha Cunda, and said to him: "Friend Cunda, let us go to the venerable Channa and ask about his illness." Then the venerable Sariputta and the venerable Maha Cunda went to the venerable Channa and exchanged greetings with him. When this courteous and amiable talk was finished, they sat down at one side and the venerable Sariputta said to the venerable Channa: "I hope you are getting well, friend Channa, I hope you are comfortable. I hope your painful feelings are subsiding and not increasing, and that their subsiding, not their increase, is apparent."
Channa: "Friend Sariputta, I am not getting well, I am not comfortable. My painful feelings are increasing, not subsiding;...(as Sutta 143)...their increase and not their subsiding is apparent. I shall use the knife to end my knife, friend Sariputta; I have no desire to live."
Sariputta: "Let the venerable Channa not use the knife. Let the venerable Channa live. We want the venerable Channa to live. If he lacks suitable food, I will go in search of suitable food for him. If he lacks suitable medicine, I will go in search of suitable medicine for him. If he lacks a proper attendant, I will attend on him. Let the venerable Channa not use the knife. Let the venerable Channa live. We want the venerable Channa to live."
Channa: "Friend Sariputta, it is not that I have no suitable food and medicine or no proper attendant. But rather, friend Sariputta, the Teacher has long been worshiped by me with love, not without love; for it is proper for the disciple to worship the Teacher with love, not without love. Friend Sariputta, remember this: the bhikkhu Channa will use the knife blamelessly." Sariputta: "We would ask the venerable Channa certain questions, if the venerable Channa finds it opportune to reply."
Channa: "Ask, friend Sariputta. When I have heard, I shall know." Sariputta: "Friend Channa, do you regard the eye, eye-consciousness, and things cognizable by the mind through eye-consciousness thus: 'This is mine, this I am, this is my self'? Do you regard the ear...the nose...the tongue...the body...the mind, mind-consciousness, and things cognizable by the mind through mind-consciousness thus: 'This is mine, this I am, this is my self'?"
Channa: "Friend Sariputta, I regard the eye, eye-consciousness, and things cognizable by the mind through eye-consciousness thus: 'This is not mine, this I am not, this is not my self.' I regard the ear...the nose...the tongue...the body...the mind, mind-consciousness, and things cognizable by the mind through mind-consciousness thus: 'This is not mine, this I am not, this is not my self.'" Sariputta: "Friend Channa, what have you seen, what have you directly known in the eye, in eye-consciousness, and in things cognizable by the mind through eye-consciousness, that you regard them thus: 'This is not mine, this I am not, this is not my self'? What have you seen, what have you directly known in the ear...in the nose...in the tongue...in the body...in the mind, in mind-consciousness, and in things cognizable by the mind through mind-consciousness, that you regard them thus: 'This is not mine, this I am not, this is not my self'?"
Channa: "Friend Sariputta, it is through seeing cessation, through directly knowing cessation in the eye, in eye-consciousness, and in things cognizable by the mind through eye-consciousness, that I regard them thus: 'This is not mine, this I am not, this is not my self.' It is through seeing cessation, through directly knowing cessation in the ear...in the nose...in the tongue...in the body...in the mind, in mind-consciousness, and in things cognizable by the mind through mind-consciousness, that I regard them thus: 'This is not mine, this I am not, this is not my self.'"
When this was said, the venerable Maha Cunda said to the venerable Channa:"Therefore, friend Channa, this instruction of the Blessed One's is to be constantly given attention: "There is wavering in one who is dependent, there is no wavering in one who is independent; when there is no wavering, there is tranquility; when there is tranquility, there is no bias; when there is no bias, there is no coming and going; when there is no coming and going, there is no passing away and reappearing; when there is no passing away and reappearing, there is no here nor beyond nor in between. This is the end of suffering.'"
Then when the venerable Sariputta and the venerable Maha Cunda had advised the venerable Channa thus, they rose from their seats and went away. Then, soon after they had gone, the venerable Channa used the knife to end his life. Then the venerable Sariputta went to the Blessed One, and after paying homage to him, he sat down at one side and said to the Blessed One: "Venerable sir, the venerable Channa has used the knife. What is his destination, what is his future course?"
Buddha: "Sariputta, didn't the bhikkhu Channa declare to you his blamelessness?" Sariputta: "Venerable sir, there is a Vajjian village called Pubbajira. There the venerable Channa had families that were his friends, families that were his intimates, families that were blameworthy."
Buddha: "There are those families that were friends of the bhikkhu Channa, Sariputta, families that were his intimates, families that were blameworthy; but I do not say that to this extent he was blameworthy. Sariputta, when one lays down this body and clings to a new body, then I say one is blameworthy. There was none of that in the bhikkhu Channa; the bhikkhu Channa used the knife blamelessly."
That is what the Blessed One said. The venerable Sariputta was satisfied and delighted in the Blessed One's words.
In summary, the venerable Channa was gravely ill, takes his own life despite the attempts of two monks namely Maha Cunda and Sariputta who tried to dissuade him. Venerable Sariputta questions him on his understanding of Dhamma and Maha Cunda recites for him a saying of the Buddha warning against the wavering that results from attachments. Later, after Channa has 'taken the knife' and Sariputta questions the Buddha as to Channa's fate. The Buddha states that his was a blameless end as he has lay down this body and does not cling to a new body.
References: 1. www.accesstoinsight.org 2. https://suttacentral.net/ 3. The Middle discourses of the Buddha (Bhikkhu Bodhi)