صحيح البخاري

Narrated Aisha:

One night the Prophet (ﷺ) was unable to sleep and said, "Would that a righteous man from my companions guarded me tonight." Suddenly we heard the clatter of arms, whereupon the Prophet (ﷺ) said, "Who is it?" It was said, "I am Sa`d, O Allah's Messenger! I have come to guard you." The Prophet (ﷺ) then slept so soundly that we heard him snoring. Abu `Abdullah said: `Aisha said: Bilal said, "Would that I but stayed overnight in a valley with Idhkhir and Jalil (two kinds of grass) around me (i.e., in Mecca)." Then I told that to the Prophet (ﷺ) .