Kimilasutta
Evaṁ me sutaṁ— ekaṁ samayaṁ bhagavā kimilāyaṁ viharati niculavane. Atha kho āyasmā kimilo yena bhagavā tenupasaṅkami; upasaṅkamitvā bhagavantaṁ abhivādetvā ekamantaṁ nisīdi. Ekamantaṁ nisinno kho āyasmā kimilo bhagavantaṁ etadavoca: “ko nu kho, bhante, hetu ko paccayo yena tathāgate parinibbute saddhammo na ciraṭṭhitiko hotī”ti?
With Kimbila
So I have heard. At one time the Buddha was staying near Kimbilā in the Freshwater Mangrove Wood. Then Venerable Kimbila went up to the Buddha, bowed, sat down to one side, and said to him: “What is the cause, sir, what is the reason why the true teaching does not last long after the final quenching of the Realized One?”