Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates: A disbelieving man became a guest of the Prophet Muhammad (peace and blessings be upon him). By the order of the Prophet (peace be upon him), milk from a goat was milked for him and he drank it. Then milk from a second goat was milked and he drank that as well, until he drank the milk of seven goats. Then in the morning, he accepted Islam. By the order of the Prophet (peace be upon him), milk from one goat was milked for him and he drank it. Then by the order of the Prophet (peace be upon him), milk from a second goat was milked for him, but he could not finish it. (At this point) the Prophet (peace be upon him) said: "Indeed, a believer drinks in one intestine, and a disbeliever drinks in seven intestines."
Hadith Referenceصحیح ابن حبان / كتاب الإيمان / 162
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - انظر ما قبله.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط مسلم.