Abdullah bin Abbas reported,

I spent the night at the home of my aunt Maymuna. 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 minimal), and stood to pray. So I performed ablution similar to his, then came and stood on his left side (Sufyan sometimes said, on his left). He turned me around and placed me on his right side, then prayed as long as Allah willed. Then he lay down and slept until he snored. Then the caller came and informed him about the prayer, so he got up with him for the prayer and prayed without performing ablution.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 عبد الله بن 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 الانبياء وحي، ثم قرأ: {إني أرى في المنام أني أذبحك} [الصافات: ١٠٢].