مسند أحمد

it was narrated that Abu Salih, the freed slave of `Uthman, said: I heard `Uthman in Mina saying: O people, I shall tell you a hadeeth that I heard from the Messenger of Allah (ﷺ) . He said: `Standing guard on the border for one day for the sake of Allah is better than one thousand ordinary days, so let a man stand on guard at the border as much as he wants.” [`Uthman] said; Have I conveyed [the message]? They said: Yes. He said: O Allah, bear witness.