Ubaydullah bin 'Abdullah bin 'Utba عبيد الله بن عبد الله بن عتبة بن مسعود · The Book on Purification

"I entered upon the Prophet with a son of mine who was not yet eating food. He urinated on him, so he called for water which he sprinkled over it."

the Prophet drank milk. Then he called for water to rinse out his mouth. Then he said: "Indeed it has fat." There are narrations on this topic from Sahl bin Sa'd As-Sa'idi and Umm Salamah. Abu Eisa said: this Hadith is Hasan Sahih. Some of the people of knowledge held the view that one is to wash the mouth after drinking milk and this is recommended according us. Some others did not hold the view that one is to wash…