I heard Messenger of Allah ﷺ saying, "While I was sleeping, I saw that a cup full of milk was brought to me and I drank of it and gave the remaining of it to ʿUmar bin Al-Khattab." They asked. What have you interpreted (about the dream)? O Messenger of Allah ﷺ?" The Prophet ﷺ said. "(It is Religious) knowledge." (Using translation from Bukhārī 7032)   

سَمِعْنَا رَسُولَ اللهِ ﷺ يَقُولُ «بَيْنَا أَنَا نَائِمٌ أُتِيتُ بِقَدَحٍ فَشَرِبْتُ مِنْهُ ثُمَّ أَعْطَيْتُ فَضْلِي عُمَرَ بْنَ الْخَطَّابِ» قَالُوا فَمَا أَوَّلْتَهُ يَا رَسُولَ اللهِ؟ قَالَ «الْعِلْمُ» خَالَفَهُ مَعْمَرٌ  

While I was asleep I saw (in a dream) a cup containing milk being presented to me. I took out of that until I perceived freshness being reflected through my nails. Then I presented the leftover to 'Umar b. Khattab. They said: Messenger of Allah: How do you interpret it? He said: This implies knowledge. (Using translation from Muslim 2391a)   

كَانَ رَسُولُ اللهِ ﷺ يُحَدِّثُ يَقُولُ «بَيْنَا أَنَا نَائِمٌ رَأَيْتُنِي أُتِيتُ بِقَدَحٍ فَشَرِبْتُ مِنْهُ حَتَّى إِنِّي لَأَرَى الرِّيَّ يَجْرِي فِي أَظْفَارِي ثُمَّ أَعْطَيْتُ فَضْلِي عُمَرَ بْنَ الْخَطَّابِ» قَالُوا فَمَا ذَلِكَ يَا رَسُولَ اللهِ؟ قَالَ «الْعِلْمُ»