Yahya related to me from Malik from Hisham ibn Urwa that Zuyayd ibn as-Salt said, "I went with Umar ibn al-Khattab to Juruf and he looked down and noticed that he had had a wet dream and had prayed without doing ghusl. He exclaimed, 'By Allah I realise that I have had a wet dream and did not know it and have not done ghusl.' So he did ghusl and washed off whatever he saw on his garment, and sprinkled with water whatever he did not see.Then he gave the adhan or the iqama and prayed in the midmorning."  

أَنَّهُ قَالَ خَرَجْتُ مَعَ عُمَرَ بْنِ الْخَطَّابِ إِلَى الْجُرُفِ فَنَظَرَ فَإِذَا هُوَ قَدِ احْتَلَمَ وَصَلَّى وَلَمْ يَغْتَسِلْ فَقَالَ وَاللَّهِ مَا أَرَانِي إِلاَّ احْتَلَمْتُ وَمَا شَعَرْتُ وَصَلَّيْتُ وَمَا اغْتَسَلْتُ قَالَ فَاغْتَسَلَ وَغَسَلَ مَا رَأَى فِي ثَوْبِهِ وَنَضَحَ مَا لَمْ يَرَ وَأَذَّنَ أَوْ أَقَامَ ثُمَّ صَلَّى بَعْدَ ارْتِفَاعِ الضُّحَى مُتَمَكِّنًا  

[Machine] And by Allah, I think that I have slept, and not felt, prayed, and not washed. He said, "Then wash and clean what you have seen on your clothing and sprinkle what you have not seen. Then call the adhan and establish the prayer, then pray after the height of the morning.  

وَاللهِ مَا أَظُنُّ إِلَّا وَأَنِّي قَدِ احْتَلَمَتُ وَمَا شَعَرْتُ وَصَلَّيْتُ وَمَا اغْتَسَلَتُ قَالَ فَاغْتَسَلَ وَغَسَلَ مَا رَأَى فِي ثَوْبِهِ وَنَضَحَ مَا لَمْ يَرَ وَأَذَّنَ وَأَقَامَ ثُمَّ صَلَّى بَعْدَ ارْتِفَاعِ الضُّحَى مُتَمَكِّنًا  

"عَنْ زُبَيْدِ بْنِ الصَّلْتِ قَالَ: خرجتُ مع عمر بن الخطاب إلى الْجُرفِ فنظرَ فإذَا هو قد احتلَم وَصلَّى ولم يغتسل فقال: واللَّه ما أرانِى إلا قد احتلمتُ وما شَعَرْتُ، وصليت وما اغتسلت، فاغتسلَ وغسل ما رأى في ثوبه، وَنَضَح مَا لَمْ يَرَ وأذَّنَ وَأقَامَ، ثم صلَّى -بعد ارتفاع الشمس- الضُّحى مُتَمَكِّنًا".