Mishkat al-Masabih 2868
Abu Huraira said God’s Messenger forbade two transactions combined in one (Making part-payment with the promise of the remainder later:
or selling an article for a stated price on condition that the buyer sells article for a stated price. 

Malik, Tirmidhi, Abu Dawud and Nasa‘i transmitted it.
وَعَنْ أَبِي هُرَيْرَةَ قَالَ: نَهَى رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَنْ بَيْعَتَيْنِ فِي بيعةٍ. رَوَاهُ مَالك وَالتِّرْمِذِيّ وَالنَّسَائِيّ