Muwatta Malik, Book 31, Hadith 1328 (In-Book) ⓘ
Yahya related to me from Malik that Abu'z-Zinad heard Said ibn al-Musayyab say, "There is usury only in gold or silver or what is weighed or measured of what is eaten or drunk."
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ أَبِي الزِّنَادِ، أَنَّهُ سَمِعَ سَعِيدَ بْنَ الْمُسَيَّبِ، يَقُولُ لاَ رِبًا إِلاَّ فِي ذَهَبٍ أَوْ فِضَّةٍ أَوْ مَا يُكَالُ أَوْ يُوزَنُ بِمَا يُؤْكَلُ أَوْ يُشْرَبُ .
also referenced under: Book 31, Hadith 37 (USC-MSA)