سورة Al-Imran ( The Famiy of Imran ) - الآية 154

Then, after sorrow, He sent down unto you a security-- slumber coming over a section of you; While anot her section, concerned about themselves, bethought of Allah unjustly: the thought of paganism. They said: have we aught at all of the affair? Say thou: the affair is wholly Allah's. They hide within themselves that which they disclose not unto thee, saying: had we aught of the affair, we would not have been slain here. Say thou: had ye stayed in your houses, even then those decreed to be slain would surely have gone forth to their places of slaughter; and this happened in order that he might prove that which was in your breasts, and purge that which was in your hearts; and Allah is Knower of that which is in the breasts.