The Discourse about Reflecting

Thus I heard: At one time the Gracious One was dwelling near Sāvatthī, in Jeta’s Wood, at Anāthapiṇḍika’s monastery. Then at that time the Gracious One was sitting reflecting on his own abandonment of countless bad, unwholesome things, and how through development countless wholesome things had come to fulfilment.
Then the Gracious One, having understood the significance of it, on that occasion uttered this exalted utterance:

“Before it was, then it wasn’t; before it wasn’t, then it was;
It was not, and it will not be, and at present it is not found.”