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 ‏.‏

Yahya related to me from Malik that Abu'z-Zinad heard Said ibnal-Musayyab say, "There is usury only in gold or silver or what isweighed or measured of what is eaten or drunk." Translation Not Available

Book reference: Muwatta Imam Malik Book 31 Hadith 1328
Web reference: Muwatta Imam Malik Book 31 Hadith 37