The paper's subject is whether one is justified to pray for an event that has already happened from the point of view of the individual who is praying. About this, there are several possibilities, all of which I will consider: a) the past event is not known to the one who prays, b) it is known by them to have happened in a way which is not the desired one by the one praying and c), it is known to have happened according to their wishes. It also deals with two derived problems: if knowledge and ignorance are essential to our possibility of petitioning for something in the past, should we remain willfully ignorant about the past in order to pray to God so that it happened as we desire? Also, once we come to know that the past event did not go about as we desire, is it reasonable to pray to God so that our knowledge about the past is incorrect?