Text: Deut 7:9
'Know therefore that the Lord your God, He is God, the faithful God, who keeps covenant and mercy with them that love Him and keeps His commandments to a thousand generations'
Long before Abraham had a son, God made a covenant with him. God told him that He would give his descendants the land in which Abraham dwelt as a stranger then. He also told Abraham that all that would happen after His descendants have been slaves in a foreign land. Abraham believed God and God saw it as an act of righteousness. The faithfulness of God is seen in the fact that God gave Abraham a son and even after Abraham died, He gave Canaan to Abraham's descendants as He promised. Because He made Abraham an everlasting covenant, it didn't matter whether Abraham was still alive or not. God brought to pass every single promise He made to him.
We must understand that God is not a man that makes a promise and reneges on the promise. Like Abraham, we must keep our own side of the covenant by keeping His commandments (obeying Him to show that we love Him) then we keep believing in Him to fulfill His promise because '...he who doubts is like a wave of the sea driven and tossed by the wind. For let not that man think that he will receive anything of the Lord' (Jam 1:6,7).