Battles (Kitab Al-Malahim)
Dawud :: Book 37 : Hadith 4336
Narrated Sa'd ibn AbuWaqqas:
The Prophet (peace_be_upon_him) said: I hope my community will not fail to maintain their position in the sight of their Lord if He delays them half a day. Sa'd was asked: How long is half a day? He said: It is five hundred years.