Sunan an-Nasa'i 3704

It was narrated from Ibn Juraij, from Al-Hasan bin Muslim, from Tawus that the Messenger of Allah said:"It is not permissible for anyone to give a gift then take it back, except a father." Tawus said: "I used to hear the boys say: 'O you who goes back to his vomit!' But I did not realize that the Messenger of Allah had said this as a parable, until we heard that he used to say: 'The likeness of the one who gives a gift then takes it back, is that of the dog which eats its vomit