Sahih al-Bukhari, Hadith 2165 ⓘ
Narrated `Abdullah bin `Umar: Allah's Messenger said, "You should not try to cancel the purchases of one another (to get a benefit thereof), and do not go ahead to meet the caravan (for buying the goods) (but wait) till it reaches the market."
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، أَخْبَرَنَا مَالِكٌ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ ـ رضى الله عنهما ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لاَ يَبِيعُ بَعْضُكُمْ عَلَى بَيْعِ بَعْضٍ، وَلاَ تَلَقَّوُا السِّلَعَ حَتَّى يُهْبَطَ بِهَا إِلَى السُّوقِ " .
also referenced under: Book 34, Hadith 116 (In-Book) & Volume 3, Book 34, Hadith 374 (USC-MSA)