It’s like the moon in the waxing fortnight. Whether by day or by night, its beauty, roundness, light, and diameter and circumference only grow. In the same way, whoever has faith, conscience, prudence, energy, and wisdom when it comes to skillful qualities can expect growth, not decline, in skillful qualities, whether by day or by night.
At Naḷakapāna the Buddha invites Sāriputta to teach. He speaks of ten qualities that lead to decline or non-decline.