Quran 33.14-16
If the enemy had entered from all sides and they had been exhorted to treachery, they would have committed it, and would have hesitated thereupon but little. And verily they had already sworn unto Allah that they would not turn their backs (to the foe). An oath to Allah must be answered for. Say: Flight will not avail you if ye flee from death or killing, and then ye dwell in comfort but a little while.