Sunnah.com reference : Book 7, Hadith 69English translation : Book 7, Hadith 0Arabic reference : Book 7, Hadith 835
Muslim has:
"and so is (that which is sold by) weight."
وَلِمُسْلِمٍ: 
" وَكَذَلِكَ اَلْمِيزَانُ " 1‏ .‏‏1 ‏- مسلم ( 1593 )‏ ( 94 )‏.‏