Muwatta Malik, Book 31, Hadith 23 (USC-MSA)

Yahya related to me from Malik from Nafi from Abdullah ibn Umar that the Messenger of Allah, may Allah bless him and grant him peace, forbade muzabana. Muzabana was selling fresh dates for dried dates by measure, and selling grapes for raisins by measure.

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم نَهَى عَنِ الْمُزَابَنَةِ وَالْمُزَابَنَةُ بَيْعُ الثَّمَرِ بِالتَّمْرِ كَيْلاً وَبَيْعُ الْكَرْمِ بِالزَّبِيبِ كَيْلاً ‏.‏

sunnah.com

also referenced under: Book 31, Hadith 1316 (In-Book)