Giver buying the gift from the person to whom it was given
Question

                A man gave his brother a car as a gift, then the one to whom the gift was given wanted to sell the car. Can the one who gave the car as a gift buy it or is it not permissible for him to buy it?.
Praise be to Allah.It is not permissible for the one who gave the gift to buy the thing he gave to his brother. It 
    was narrated that ‘Umar (may Allaah be pleased with him) said: I gave a horse (to someone to use in jihad) for the sake of Allaah, and its owner 
    neglected it. I thought that he would sell it  for a cheap price, and I asked the Messenger of Allaah  (peace and blessings of Allaah be upon 
    him) about that. He said, “Do not buy it from him even if he sells it to you for a dirham, for the one who takes back his charity is like the dog 
    that goes back to its own vomit.” Narrated by al-Bukhaari, 2623; Muslim, 1620. 
And Allaah is the Source of strength.