Saṅgāravasutta
Atha kho saṅgāravo brāhmaṇo yena bhagavā tenupasaṅkami; upasaṅkamitvā bhagavatā saddhiṁ sammodi. Sammodanīyaṁ kathaṁ sāraṇīyaṁ vītisāretvā ekamantaṁ nisīdi. Ekamantaṁ nisinno kho saṅgāravo brāhmaṇo bhagavantaṁ etadavoca: “ko nu kho, bho gotama, hetu ko paccayo, yena kadāci dīgharattaṁ sajjhāyakatāpi mantā nappaṭibhanti, pageva asajjhāyakatā? Ko pana, bho gotama, hetu ko paccayo, yena kadāci dīgharattaṁ asajjhāyakatāpi mantā paṭibhanti, pageva sajjhāyakatā”ti?
With Saṅgārava
Then Saṅgārava the brahmin went up to the Buddha, and exchanged greetings with him. When the greetings and polite conversation were over, Saṅgārava sat down to one side, and said to the Buddha: “What is the cause, Worthy Gotama, what is the reason why sometimes even hymns that are long-rehearsed don’t spring to mind, let alone those that are not rehearsed? And why is it that sometimes even hymns that are long-unrehearsed spring to mind, let alone those that are rehearsed?”