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."
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا سَعِيدُ بْنُ عُفَيْرٍ، قَالَ حَدَّثَنِي اللَّيْثُ، قَالَ حَدَّثَنِي عُقَيْلٌ، عَنِ ابْنِ شِهَابٍ، عَنْ حَمْزَةَ بْنِ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ ابْنَ عُمَرَ، قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " بَيْنَا أَنَا نَائِمٌ أُتِيتُ بِقَدَحِ لَبَنٍ، فَشَرِبْتُ حَتَّى إِنِّي لأَرَى الرِّيَّ يَخْرُجُ فِي أَظْفَارِي، ثُمَّ أَعْطَيْتُ فَضْلِي عُمَرَ بْنَ الْخَطَّابِ ". قَالُوا فَمَا أَوَّلْتَهُ يَا رَسُولَ اللَّهِ قَالَ " الْعِلْمَ ".
sunnah.com