Abdullah bin Abbas reported,

I spent a night at the home of my aunt Maymun. The Prophet ﷺ got up during the night, and at some point in the night he rose, performed a light ablution from a hanging waterskin (Amr would describe it as light and sparing), and stood up to pray.I performed an ablution similar to his, then came and stood on his left side (Sufyan sometimes said, on his left). He moved me around and placed me on his right side. He prayed for as long as Allah willed, then lay down and slept until I could hear him breathing deeply. Then the caller came and announced the prayer, so he got up with him and went to pray, and he prayed without performing ablution again.We said to Amr, "Some people say that the Messenger of Allah's ﷺ eyes sleep but his heart does not sleep."Amr replied, "I heard Ubayd bin Umayr say, 'The dreams of prophets are revelation,' then he recited, "Indeed, I have seen in a dream that I am sacrificing you" [Saffat 37:102]."

عن ابن عباس قال

بت عند خالتي ميمونة ليلة، فقام النبي ﷺ من الليل، فلما كان في بعض الليل قام النبي ﷺ، فتوضأ من شن معلق وضوءا خفيفا،- يخففه عمرو ويقلله-، وقام يصلي، فتوضأت نحوا مما توضأ، ثم جئت، فقمت عن يساره- وربما قال سفيان: عن شماله- فحولني، فجعلني عن يمينه، ثم صلى ما شاء الله، ثم اضطجع، فنام حتى نفخ، ثم أتاه المنادي، فآذنه بالصلاة، فقام معه إلى الصلاة، فصلى، ولم يتوضأ. قلنا لعمرو: إن ناسا يقولون: إن رسول الله ﷺ تنام عينه ولا ينام قلبه، قال عمرو: سمعت عبيد بن عمير يقول: رؤيا الأنبياء وحي، ثم قرأ: {إن أرى في المنام أن أذبحك}