Al-Kāfi
Hadith 6505- مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ وَعِدَّةٌ مِنْ أَصْحَابِنَا عَنْ سَهْلِ بْنِ زِيَادٍ عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ أَبِي نَصْرٍ عَنْ أَبَانٍ عَنْ عَبْدِ الرَّحْمَنِ بْنِ أَبِي عَبْدِ اللهِ قَالَ قُلْتُ لأبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) أَيَجُوزُ قَفِيزٌ مِنْ حِنْطَةٍ بِقَفِيزَيْنِ مِنْ شَعِيرٍ فَقَالَ لا يَجُوزُ إِلا مِثْلا بِمِثْلٍ ثُمَّ قَالَ إِنَّ الشَّعِيرَ مِنَ الْحِنْطَةِ.
5. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad and a number of our people have narrated from Sahl ibn Ziyad from Ahmad ibn Muhammad from ibn abu Nasr from Aban from ‘Abd al-Rahman ibn abu ‘Abd Allah who has said the following: “This is concerning my question before abu ‘Abd Allah (a.s.), if it is permissible to exchange one Qafiz (a certain unit of measurement) of wheat for two Qafiz of barley. He (the Imam) said, ‘No, it is not permissible unless they are of equal quantities.’ He (the Imam) then said, ‘Barley is from wheat.’”