'Abdul-Muhaimin bin 'Abbas bin Sahl bin Sa'd As-Sa'di narraed from his father, from his grandfather, that:
The Messenger of Allah said: "Rinse your mouths after drinking milk, for it has some greasiness in it." (ES)
English reference (ES): Vol. 1, Book 1, Hadith 500 (ES)
Arabic reference (ES): Book 1, Hadith 539 (ES)