(58) باب لاَ يَبِيعُ عَلَى بَيْعِ أَخِيهِ وَلاَ يَسُومُ عَلَى سَوْمِ أَخِيهِ، حَتَّى يَأْذَنَ لَهُ أَوْ يَتْرُكَ
Narrated `Abdullah bin `Umar:
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."
Reference: Sahih al-Bukhari 2139
In-book reference: Book 34, Hadith 91
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 34, Hadith 349