Hisham bin Urwah (may Allah have mercy on him) narrates from his father that Zubayd bin al-Salt went out with Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) to al-Juruf. He looked and saw that he had had a wet dream. He said: By Allah, I think nothing other than that I have had a wet dream, and I did not even realise it, and I prayed without performing the ritual bath (ghusl). Then he performed the ritual bath, washed what he saw on his garment and sprinkled water on what he did not see, then gave the adhan and the iqamah, then he prayed calmly after the sun had risen high.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1901