'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." (DE)
English reference (DE): Vol. 1, Book 1, Hadith 500 (DE)
Arabic reference (DE): Book 1, Hadith 539 (DE)