A disbelieving guest came to stay with the Messenger of Allah ﷺ, so the Messenger of Allah ﷺ ordered that a sheep be milked for him, and he drank its milk. Then another was milked, and he drank that. Then another, and he drank that as well, until he had drunk the milk of seven sheep.The next morning, he embraced Islam. The Messenger of Allah ﷺ then ordered that a sheep be milked for him, and he drank its milk. Then another was ordered for him, but he could not finish it.The Messenger of Allah ﷺ said, "The believer drinks with one stomach, while the disbeliever drinks with seven stomachs."
أن رسول الله ﷺ ضافه ضيف كافر، فأمر له رسول الله ﷺ بشاة فحلبت، فشرب حلابها، ثم أخرى فشربه، ثم أخرى فشربه، حتى شرب حلاب سبع شياه، ثم إنه أصبح، فأسلم، فأمر له رسول الله ﷺ بشاة فحلبت، فشرب حلابها، ثم أمر له بأخرى، فلم يستتمها، فقال رسول الله ﷺ: المؤمن يشرب في معى واحد، والكافر يشرب في سبعة أمعاء.
Malik reported it in the Description of the Prophet ﷺ (10) from Suhayl bin Abu Salih, from his father, from Abu Hurairah, and he mentioned it. Muslim also reported it in the Book of Drinks (2063:186) through the route of Malik, in a similar manner.