The Buddha reviews the multitude of harmful and unwholesome mental qualities he has abandoned, and the multitude of wholesome mental qualities he has developed to completion.
Thus I have heard - At one time, the Blessed One was dwelling at Sāvatthi, in Jeta's Grove, Anāthapiṇḍika's park. Now, at that time, the Blessed One was sitting, reviewing the multitude of harmful and unwholesome mental qualities he had abandoned, and the multitude of wholesome mental qualities that he had developed to completion.
Then the Blessed One, having perceived that multitude of harmful and unwholesome qualities had been abandoned by him, and that multitude of wholesome qualities had been developed to completion, at that time uttered this inspired utterance:
"There was in the past, then there was not,
there was not in the past, then there was;
It neither was, nor will it be,
nor does it exist now." [1]
[1] I suspect that the verse refers to a review of harmful and unwholesome mental qualities done one at a time. This process is to show that an awakened being carefully examines and verifies things as they have come to be instead of assuming or jumping to conclusions.
Related Teachings:
Reviewing one's failings and successes from time to time (AN 8.7) - The Buddha advises the bhikkhus to review their own failings and the failings of others, and to overcome acquisitions, loss, fame, disrepute, honor, dishonor, evil wishes, and evil friendship.
Steadying the mind against the poisons of greed, hate and delusion (AN 4.117) - The Buddha's teachings when practiced become a support for the mind, allowing it to remain steady in situations that once used to shake it up.
