ENOfficial
Narrated 'Abdullah bin 'Umar: The Messenger of Allah (ﷺ) as saying: None of you must buy in opposition to one another ; and do not go out to meet the merchandise, (but one must wait) till it is brought down to the market.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ الْقَعْنَبِيُّ، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لاَ يَبِعْ بَعْضُكُمْ عَلَى بَيْعِ بَعْضٍ وَلاَ تَلَقَّوُا السِّلَعَ حَتَّى يُهْبَطَ بِهَا الأَسْوَاقَ " .
sunnah.com