Sahih al-Bukhari, Volume 3, Book 34, Hadith 336 (USC-MSA) ⓘ
Narrated `Abdullah ibn `Umar: Allah's Messenger said, "He who buys foodstuff should not sell it till he is satisfied with the measure with which he has bought it.
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 " مَنِ ابْتَاعَ طَعَامًا فَلاَ يَبِيعُهُ حَتَّى يَسْتَوْفِيَهُ " .
also referenced under: Book 34, Hadith 78 (In-Book) & Hadith 2126 (DarusSalam)