Be aware of a day when regret will be of no use.

{  Do they [then] wait for anything except that the angels should come to them or your Lord should come or that there come some of the signs of your Lord? The Day that some of the signs of your Lord will come no soul will benefit from its faith as long as it had not believed before or had earned through its faith some good. Say, "Wait. Indeed, we [also] are waiting."  }