The Messenger of Allah ﷺ began to lead (the people) in the dawn prayer. He then signalled with his hand: (Stay) at your places. (Then he entered his home). He then returned while drops of water were coming down from him (from his body) and he led them in prayer.  

أَنَّ رَسُولَ اللَّهِ ﷺ دَخَلَ فِي صَلاَةِ الْفَجْرِ فَأَوْمَأَ بِيَدِهِ أَنْ مَكَانَكُمْ ثُمَّ جَاءَ وَرَأْسُهُ يَقْطُرُ فَصَلَّى بِهِمْ  

He uttered TAKBIR (Allahu akbar), and in the end : when he finished the prayer, he said : I am a human being; I was sexually defiled. Abu Dawud said : This tradition has been narrated al-Zuhri from Abu Salamah b. ‘Abd al-Rahman on the authority of Abu Hurairah. It says: When he stood at the place of prayer, we waited for his utterance of takbir (Allah-u akbar).He went away and said : (remain) as you were. Another version on the authority of Muhammad reporting from the Prophet ﷺ says: He uttered takbir (Allah-u-Akbar) and then made a sign to the people, meaning "sit down". He then went away and took a bath. This tradition has also been narrated through a different chain. It says: The Messenger of Allah ﷺ uttered takbir (Allah-u-akbar) in a prayer. Abu Dawud said: Another version through a different chain says; The Prophet (May peace be upon him) uttered takbir (Allah-u akbar).  

إِنَّمَا أَنَا بَشَرٌ وَإِنِّي كُنْتُ جُنُبًا  

The prayer (in congregation) began and people stood in their rows. The Messenger of Allah (May peace be upon him) came out (from his residence). When he stood at his proper place he recalled that he did not take a bath. He then said to the people: (Remain standing) at your places. Then he returned to his house and came out upon us after taking a bath while the drops of water were coming down from his head. We were standing in the rows (of prayer). This is the version of Ibn Harb. ‘Ayyash reported in his version: we kept on waiting for him while we were standing until he came upon us after he had taken a bath.  

أُقِيمَتِ الصَّلاَةُ وَصَفَّ النَّاسُ صُفُوفَهُمْ فَخَرَجَ رَسُولُ اللَّهِ ﷺ حَتَّى إِذَا قَامَ فِي مَقَامِهِ ذَكَرَ أَنَّهُ لَمْ يَغْتَسِلْ فَقَالَ لِلنَّاسِ مَكَانَكُمْ ثُمَّ رَجَعَ إِلَى بَيْتِهِ فَخَرَجَ عَلَيْنَا يَنْطُفُ رَأْسُهُ وَقَدِ اغْتَسَلَ وَنَحْنُ صُفُوفٌ وَهَذَا لَفْظُ ابْنِ حَرْبٍ وَقَالَ عَيَّاشٌ فِي حَدِيثِهِ فَلَمْ نَزَلْ قِيَامًا نَنْتَظِرُهُ حَتَّى خَرَجَ عَلَيْنَا وَقَدِ اغْتَسَلَ