It was narrated from 'Amr bin Shu'aib, from Tawus, from Ibn 'Umar and Ibn 'Abbas, that they said:"The Messenger of Allah said: 'It is not permissible for anyone to give a gift then take it back, except a father with regard to what he gives to his son. The likeness of the one who gives a gift then takes it back, is that of the dog which eats then when it is full it vomits, then it goes back to its vomit