Sahih Bukhari

Narrated Ibn `Umar:Allah's Messenger (ﷺ) said, ""While I was sleeping, I saw that a cup full of milk was brought to me and I drank my fill till I noticed (the milk) its wetness coming out of my nails. Then I gave the remaining milk to `Umar Ibn Al-Khattab"" The companions of the Prophet (ﷺ) asked, ""What have you interpreted (about this dream), O Allah's Messenger (ﷺ)?"" He replied, ""(It is religious) knowledge.""