Al-Kāfi
Hadith 6696- الْحُسَيْنُ بْنُ مُحَمَّدٍ عَنْ مُعَلَّى بْنِ مُحَمَّدٍ عَمَّنْ ذَكَرَهُ عَنْ أَبَانٍ عَنْ مُحَمَّدٍ عَنْ أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) قَالَ مَا كَانَ مِنْ طَعَامٍ مُخْتَلِفٍ أَوْ مَتَاعٍ أَوْ شَيْءٍ مِنَ الأشْيَاءِ يَتَفَاضَلُ فَلا بَأْسَ بِبَيْعِهِ مِثْلَيْنِ بِمِثْلٍ يَداً بِيَدٍ فَأَمَّا نَظِرَةً فَلا تَصْلُحُ.
6. Al-Husayn from Muhammad has narrated from Mu’alla’ ibn Muhammad from those whom he has mentioned from Aban from Muhammad who has said the following: “Abu ‘Abd Allah (a.s.), has said, ‘In the exchange of foodstuff of different kinds or other things with different quantities is not harmful in a hand in hand transaction but it is not valid on credit.’”