Al-Kāfi - Volume 6 > Eating with the Right Hand
Hadith #3

عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ أَحْمَدَ بْنِ أَبِي عَبْدِ اللَّهِ عَنْ عُثْمَانَ بْنِ عِيسَى عَنْ سَمَاعَةَ عَنْ أَبِي عَبْدِ اللَّهِ ( عليه السلام ) قَالَ سَأَلْتُهُ عَنِ الرَّجُلِ يَأْكُلُ بِشِمَالِهِ أَوْ يَشْرَبُ بِهَا فَقَالَ لَا يَأْكُلْ بِشِمَالِهِ وَ لَا يَشْرَبْ بِشِمَالِهِ وَ لَا يَتَنَاوَلْ بِهَا شَيْئاً .

3. A number of our people have narrated from Ahmad ibn abu ‘Abd Allah from ‘Uthman ibn ‘Isa from Sama‘ah who has said the following: “I once asked abu ‘Abd Allah, ‘Alayhi al-Salam, about the case of a man who eats or drinks with his left hand. He (the Imam) said, ‘He must not eat with his left hand and must not drink with his left hand or lift up anything with it.’”