Paṭhamaavijjāpahānasutta
Atha kho aññataro bhikkhu yena bhagavā tenupasaṅkami …pe… ekamantaṁ nisinno kho so bhikkhu bhagavantaṁ etadavoca: “atthi nu kho, bhante, eko dhammo yassa pahānā bhikkhuno avijjā pahīyati, vijjā uppajjatī”ti?
Giving Up Ignorance (1st)
Then a mendicant went up to the Buddha … and said to him: “Sir, is there one thing such that by giving it up a mendicant gives up ignorance and gives rise to knowledge?”