Mātāputtasutta
Ekaṁ samayaṁ bhagavā sāvatthiyaṁ viharati jetavane anāthapiṇḍikassa ārāme. Tena kho pana samayena sāvatthiyaṁ ubho mātāputtā vassāvāsaṁ upagamiṁsu— bhikkhu ca bhikkhunī ca. Te aññamaññassa abhiṇhaṁ dassanakāmā ahesuṁ. Mātāpi puttassa abhiṇhaṁ dassanakāmā ahosi; puttopi mātaraṁ abhiṇhaṁ dassanakāmo ahosi. Tesaṁ abhiṇhaṁ dassanā saṁsaggo ahosi. Saṁsagge sati vissāso ahosi. Vissāse sati otāro ahosi. Te otiṇṇacittā sikkhaṁ apaccakkhāya dubbalyaṁ anāvikatvā methunaṁ dhammaṁ paṭiseviṁsu.
Mother and Son
At one time the Buddha was staying near Sāvatthī in Jeta’s Grove, Anāthapiṇḍika’s monastery. Now, at that time a mother and son had both entered the rainy season residence at Sāvatthī, as a monk and a nun. They wanted to see each other often. The mother wanted to see her son often, and the son his mother. Seeing each other often, they became close. Being so close, they became familiar. And being familiar, lust overcame them. With their minds swamped by lust, without resigning the training and declaring their inability to continue, they had sex.