Sahih al-Bukhari Book 34, Hadith 91
Allah's Messenger (ﷺ) said, "Do not urge somebody to return what he has already bought (i.e. in optional
sale) from another seller so as to sell him your own goods."
Rarely did the Prophet (ﷺ) fail to visit Abu Bakr's house everyday, either in the morning or in the evening. When the permission for migration to Medina was granted, all of a sudden the Prophet (ﷺ) came to us at noon and Abu Bakr was informed, who said, "Certainly the Prophet (ﷺ) has come for some urgent matter." The Prophet (ﷺ) said to Abu Bark, when the latter entered "Let nobody stay in your home." Abu Bakr said, "O Allah's Messenger (ﷺ)! There are only my two daughters (namely `Aisha and Asma') present." The Prophet (ﷺ) said, "I feel (am informed) that I have been granted the permission for migration." Abu Bakr said, "I will accompany you, O Allah's Messenger (ﷺ)!" The Prophet (ﷺ) said, "You will accompany me." Abu Bakr then said "O Allah's Messenger (ﷺ)! I have two she-camels I have prepared specially for migration, so I offer you one of them. The Prophet (ﷺ) said, "I have accepted it on the condition that I will pay its price."
Allah's Messenger (ﷺ) forbade the selling of things by a town dweller on behalf of a desert dweller; and similarly Najsh was forbidden. And one should not urge somebody to return the goods to the seller so as to sell him his own goods; nor should one demand the hand of a girl who has already been engaged to someone else; and a woman should not try to cause some other woman to be divorced in order to take her place.