The Prophet said: 'Rinse your mouths after drinking milk for there is some greasiness in it."
Sunan Ibn Majah Book 1, Hadith 232
← Previous Hadith "I heard the Messenger of Allah say: 'Perform ablution after (eating) camel meat, but do not perform ablution after (eating) mutton. Perform ablution after (drinking) camel's milk, but do not perform ablution after (drinking) sheep's milk. Perform prayer in the sheep pens but not do in the camels' Ma'atin.'"

Sunan Ibn Majah Book 1, Hadith 231 Next Hadith → "The Messenger of Allah said: 'If you drink milk, then rinse your mouths, for there is some greasiness in it.'"

Sunan Ibn Majah Book 1, Hadith 233