كتاب البيوع
7  
Business Transactions
Muslim has:
"and so is (that which is sold by) weight."
وَلِمُسْلِمٍ: " وَكَذَلِكَ اَلْمِيزَانُ " 1‏ .‏


‏1 ‏- مسلم ( 1593 )‏ ( 94 )‏.‏

Sunnah.com reference : Book 7, Hadith 69
English translation : Book 7, Hadith 0
Arabic reference : Book 7, Hadith 835