The Jataka, Vol. II, tr. by W.H.D. Rouse, , at sacred-texts.com
"Hot at top," etc. This is a story told by the Master while at Jetavana, about one who hankered after a lost wife. The Brother in question was asked by the Master if he really was lovesick. Yes, he said, so he was. "For whom?" was the next question. "For my late wife." "Brother," the Master said, "this same woman in former days was wicked, and made you eat the leavings of her paramour." Then he told this story of the past.
Once upon a time, while Brahmadatta was reigning in Benares, the Bodhisatta was born as one of a family of poor acrobats, that lived by begging. So when he grew up, he was needy and squalid, and by begging he lived.
There was at the time, in a certain village of Kāsi, a brahmin whose wife was bad and wicked, and did wrong.  And it befel that the husband went abroad one day upon some matter, and her lover watching his time went to visit the house. After she had received him, he said, "I will eat a bit before I go." So she made ready the food, and served up rice hot with sauce and curry, and gave it him, bidding him eat: she herself stood at the door, watching for the brahmin's coming. And while the lover was eating, the Bodhisatta stood waiting for a morsel.
At that moment the brahmin set his face for home. And his wife saw him drawing nigh, and ran in quickly--"Up, my man is coming!" and she made her lover go down into the store-room. The husband came in; she gave him a seat, and water for washing the hands; and upon the cold rice that was left by the other she turned out some hot rice, and set it before him. He put his hand into the rice, and felt that it was hot above and cold below. "This must be some one else's leavings," thought he; and so he asked the woman about it in the words of the first stanza:
Again and again he asked, but she, fearing lest her deed should be discovered, held her peace, Then a thought came into our tumbler's mind. "The man down in the store-room must be a lover, and this is the master of the house: the wife says nothing, for fear that her deed be made manifest. Soho! I will declare the whole matter, and show the brahmin that a man is hidden in his larder!"  And he told him the whole
matter: how that when he had gone out from his house, another had come in, and had done evil; how he had eaten the first rice, and the wife had stood by the door to watch the road; and how the other man had been hidden in the store-room. And in so saying, he repeated the second stanza:
By his top-knot he haled the man out of the store-room, and bade him take care not to do the like again; and then he went away. The brahmin rebuked and beat them both, and gave them such a lesson that they were not likely to do the same again. Afterwards he passed away to fare according to his deserts.
When the Master had ended his discourse, he declared the Truths, and identified the Birth:--at the conclusion of the Truths the lovesick Brother reached the Fruit of the First Path:--"Your late wife was then the brahmin's lady; you, the lovesick Brother, were the brahmin himself; and I was the tumbler."