"The one who takes back the gift he has given to someone is like one who eats his vomit." In another wording: "The one who takes back the charity that he gave is like a dog that vomits then eats its vomit." [Al-Bukhari]

"عن عبد الله بن عباس -رضي الله عنهما- مرفوعاً: ""العائد في هِبَتِهِ، كالعائد في قَيْئِهِ"". وفي لفظ: ""فإن الذى يعود في صدقته: كالكلب يَقِئ ُثم يعود في قيئه"". [صحيح.] - [متفق عليه.]"