It was narrated that Ibn 'Abbas (رضي الله عنه) said:

I slept in the house of my maternal aunt Maimoonah bint al-Harith. The Prophet (ﷺ) got up at night and went to relieve himself, then he came and washed his face and hands, then he slept. Then he got up at night and went to the waterskin and undid its straps, then he did a wudoo’ that was somewhere between the most complete and the most light; he did not use a lot of water but it was a proper wudoo’. Then he stood and prayed. I hid myself because I did not want him to see me watching him. Then I got up and did the same as he had done, and I stood on his left. He took hold of my neck, where the ear is, and moved me around until I was standing on his right whilst he was praying. He prayed thirteen rak'ahs, including the two [Sunnah] rak'ahs of Fajr. Then he lay down and slept until he breathed deeply, Then Bilal came and called him to pray, so he got up and prayed and did not do wudoo’ [again].