9 The word spoken to Abraham contains both a call and a promise. First, it is a call to leave his own land, a summons to a new life, the beginning of an exodus which points him towards an unforeseen future. The sight which faith would give to Abraham would always be linked to the need to take this step forward: faith "sees" to the extent that it journeys, to the extent that it chooses to enter into the horizons opened up by God’s word. This word also contains a promise: Your descendants will be great in number, you will be the father of a great nation (cf. Gen 13:16; 15:5; 22:17). As a response to a word which preceded it, Abraham’s faith would always be an act of remembrance. Yet this remembrance is not fixed on past events but, as the memory of a promise, it becomes capable of opening up the future, shedding light on the path to be taken. We see how faith, as remembrance of the future, memoria futuri , is thus closely bound up with hope.
Source: Lumen Fidei (Vatican.va)