Sahih Bukhari Volume 9, Book 91, Hadith 7029

حَدَّثَنَا يَحْيَى بْنُ بُكَيْرٍ، حَدَّثَنَا اللَّيْثُ، عَنْ عُقَيْلٍ، عَنِ ابْنِ شِهَابٍ، أَخْبَرَنِي حَمْزَةُ بْنُ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏"‏ بَيْنَا أَنَا نَائِمٌ أُتِيتُ بِقَدَحِ لَبَنٍ فَشَرِبْتُ مِنْهُ، حَتَّى إِنِّي لأَرَى الرِّيَّ يَجْرِي، ثُمَّ أَعْطَيْتُ فَضْلَهُ عُمَرَ ‏"‏‏.‏ قَالُوا فَمَا أَوَّلْتَهُ يَا رَسُولَ اللَّهِ قَالَ ‏"‏ الْعِلْمُ ‏"‏‏

Narrated By 'Abdullah bin 'Umar : I heard Allah's Apostle saying, "While I was sleeping, I saw a bowl full of milk was brought to me and I drank of it (to my fill) till I noticed its wetness flowing (in my body). Then I gave the remaining of it to 'Umar." They asked, "O Allah's Apostle! What have you interpreted (about the dream)? He said, "(It is Religious) knowledge."