The Messenger of Allah ﷺ lay awake one night while she was beside him.She said, "I asked, 'What troubles you, Messenger of Allah?'"He replied, "I wish a righteous man from among my companions would guard me tonight."She said, "While we were in that state, I suddenly heard the sound of weapons."He asked, "Who is this?"The man answered, "I am Saad bin Malik."The Prophet ﷺ asked, "What brings you here?"He replied, "I have come to stand guard over you, Messenger of Allah."She said, "Then I heard the Messenger of Allah ﷺ snoring in his sleep."
حدثنا يزيد قال أخبرنا يحيى قال سمعت عبد الله بن عامر بن ربيعة يحدث أن
أن رسول الله ﷺ سهر ذات ليلة وهي إلى جنبه قالت فقلت ما شأنك يا رسول الله قالت فقال ليت رجلا صالحا من أصحابي يحرسني الليلة قال فبينا أنا على ذلك إذ سمعت صوت السلاح فقال من هذا قال أنا سعد بن مالك فقال ما جاء بك قال جئت لأحرسك يا رسول الله قالت فسمعت غطيط رسول الله ﷺ في نومه
Its isnad is sahih. Bukhari narrated it, 6/81, no. 2885, in the chapter on jihad, and Muslim, 4/1875, no. 2410, in the chapter on the virtues of the companions, and Tirmidhi, 5/650, no. 3756, saying, hasan sahih, and Nasai in his book on the virtues of the companions, no. 113, which is a separate book from his Sunan.I point this out because many of those who work with hadith are unaware of it. In fact, the head of the hadith department at one of the well established colleges asked me about this book, and denied that it existed anywhere other than in his Sunan. This is one of the strange things I have encountered in my life.