Al-Kāfi - Volume 6 > The Milk Products
Hadith #6

عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنْ عُثْمَانَ بْنِ عِيسَى عَنْ خَالِدِ بْنِ نَجِيحٍ عَنْ أَبِي عَبْدِ اللَّهِ ( عليه السلام ) قَالَ اللَّبَنُ طَعَامُ الْمُرْسَلِينَ .

6. A number of our people have narrated from Ahmad ibn Muhammad from ‘Uthman ibn ‘Isa from Khalid ibn Najih who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘Milk is the food of the Messenger (of Allah).”’