A Sunnah with which We sentOur Messengers before you and you will not find any alteration in Our Sunnah.meaning this is what We usually do to those who reject Our Messengers and persecute them by driving the Messenger out from among themselves - the punishment comes to them. If it were not for the fact that the Prophet was the Messenger of Mercy, vengeance would have come upon them such as had never been seen before in this world.So Allah says:وَمَا كَانَ اللَّهُ لِيُعَذِّبَهُمْ وَأَنتَ فِيهِمْAnd Allah would not punish them while you are among them. (8:33)