Muwatta Malik, Book 31, Hadith 1327 (In-Book) ⓘ
Yahya related to me from Malik that he had heard that al-Oasim ibn Muhammad said, ''Umar ibn al-Khattab said, 'A dinar for a dinar, and a dirham for adirham, and a sa for a sa. Something to be collected later is not to be sold for something at hand. ' "
وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ عَنِ الْقَاسِمِ بْنِ مُحَمَّدٍ، أَنَّهُ قَالَ قَالَ عُمَرُ بْنُ الْخَطَّابِ الدِّينَارُ بِالدِّينَارِ وَالدِّرْهَمُ بِالدِّرْهَمِ وَالصَّاعُ بِالصَّاعِ وَلاَ يُبَاعُ كَالِئٌ بِنَاجِزٍ .
also referenced under: Book 31, Hadith 36 (USC-MSA)