"Some of those who met the Prophet told us that he said: 'The likeness of the one who gives (something), then takes back his gift, is that of a dog which eats, then vomits, then eats its vomit.'"
Sunan an-Nasa'i Book 32, Hadith 18
← Previous Hadith "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.'"

Sunan an-Nasa'i Book 32, Hadith 17 Next Hadith → "My father narrated to us: Ubaidullah -he is, Ibn 'Amr- narrated to us, from Sufyan, from Ibn Abi Najih, from Tawus, from Zaid bin Thabit, that the Prophet said: 'Ar-Ruqba is permissible.'"

Sunan an-Nasa'i Book 33, Hadith 1