Sahih Muslim 2410 b
The Book of the Merits of the Companions
The Virtues Of Sa'd Bin Abi Waqqas (RA)
'A'isha reported that Allah's Messenger (ﷺ) laid down on bed during one night on his arrival at Medina and said: Were there a pious person from amongst my Companions who should keep a watch for me durin. the night? She (A'isha) reported: We were in this state that we heard the clanging noise of arms. lie (the Prophet) said: Who is it? He said: This is Sa'd b. Abi Waqqas. Allah's Messenger (ﷺ) said to him: What brings you here? Thereupon he said: I harboured fear (lest any harm should come to) Allah's Messenger (ﷺ), so I came to serve as your sentinel. Allah's Messenger (ﷺ) invoked blessings upon him. He then slept. This hadith has been transmitted on the authority of Ibn Rumh with a slight variation of wording.