MN 131 Bhaddekaratta Sutta: One Fortunate Attachment 

​ Thus have i heard. 

On one occasion the Blessed One was living at Savatthi in Jeta's Grove, Anathapindika's Park. There he addressed the bhikkhus thus: "Bhikkhus, I shall teach you the summary and exposition of 'One Who Has One Fortunate Attachment.' Listen and attend closely to what I shall say."
"Yes, venerable sir," the bhikkhus replied.

The Blessed One said this: 
"Let not a person revive the past Or on the future build his hopes;
For the past has been left behind And the future has not been reached.
Instead with insight let him see Each presently arisen state;
Let him know that and be sure of it, Invincibly, unshakeably.
Today the effort must be made; Tomorrow Death may come, who knows?
No bargain with Mortality Can keep him and his hordes away,
But one who dwells thus ardently, Relentlessly, by day, by night
It is he, the Peaceful Sage has said,
Who has one fortunate attachment. "

"How, bhikkhus, does one revive the past? Thinking, 'I had such material form in the past,' one finds delight in that. Thinking, 'I had such feeling in the past,'...'I had such perception in the past,'...'I had such formations in the past,'...'I had such consciousness in the past,' one finds delight in that. That is how one revives the past. "

​ "And how, bhikkhus, does one not revive the past? Thinking, 'I had such material form in the past,' one does not find delight in that. Thinking, 'I had such feeling in the past,'...! had such perception in the past,'...! had such formations in the past,'...! had such consciousness in the past,' one does not find delight in that. That is how one does not revive the past."

"And how, bhikkhus, does one build up hope upon the future? Thinking, 'I may have such material form in the future,' one finds delight in that. Thinking, 'I may have such feeling in the future,'...'I may have such perception in the future,'...! may have such formations in the future,'...'I may have such consciousness in the future,' one finds delight in that. That is how one builds up hope upon the future. "

"And how, bhikkhus, does one not build up hope upon the future? Thinking, 'I may have such material form in the future,' one does not find delight in that. Thinking, 'I may have such feeling in the future,'...'I may have such perception in the future,'...! may have such formations in the future,'...! may have such consciousness in the future,' one does not find delight in that. That is how one does not build up hope upon the future. "

"And how, bhikkhus, is one vanquished in regard to presently arisen states? Here bhikkhus, an untaught ordinary person, who has no regard for noble ones and is unskilled and undisciplined in their Dhamma, who has no regard for true men and is unskilled and undisciplined in their Dhamma, regards material form as self, or self as possessed of material form, or material form as in self, or self as in material form. He regards feeling as self...perception as self...formations as self.....consciousness as self, or self as possessed of consciousness, or consciousness as in self, or self as in consciousness. That is how one is vanquished in regard to presently arisen states."

"And how, bhikkhus, is one invincible in regard to presently arisen states? Here, bhikkhus, a well-taught noble disciple, who has regard for noble ones and is skilled and disciplined in their Dhamma, who has regard for true men and is skilled and disciplined in their Dhamma, does not regard material form as self or self as possessed of material form, or material form as in self or self as in material form. He does not regard feeling as self...perception as self...formations as self...consciousness as self, or self as possessed of consciousness, or consciousness as in self, or self as in consciousness. That is how one is invincible in regard to presently arisen states. "

"Let not a person revive the past... Who has one fortunate attachment. "
"So it was with reference to this that it was said: 'Bhikkhus, I shall teach you the summary and exposition of "One Who Has One Fortunate Attachment"" 

That is what the Blessed One said. The bhikkhus were satisfied and delighted in the Blessed One's words. 

In summary, Buddha talks about "one who has one fortunate attachment" and describes being one in which one does not hanker after the past, yearn for the future, and in which one remains detached among things present.
Buddha mentioned a set of verses extolling the benefits of insight into the here and now, followed by an explanation.

References: 
1. www.accesstoinsight.org
2. https://suttacentral.net/
3. The Middle discourses of the Buddha (Bhikkhu Bodhi)