Read Romans 4:1-5 and 13-17
What shall we say, then, of Abraham, the father of our race? What was his experience? 2If he was put right with God by the things he did, he would have something to boast about—but not in God’s sight. 3The scripture says, “Abraham believed God, and because of his faith God accepted him as righteous.” 4Those who work are paid wages, but they are not regarded as a gift; they are something that has been earned. 5But those who depend on faith, not on deeds, and who believe in the God who declares the guilty to be innocent, it is this faith that God takes into account in order to put them right with himself.
13 When God promised Abraham and his descendants that the world would belong to him, he did so, not because Abraham obeyed the Law, but because he believed and was accepted as righteous by God. 14For if what God promises is to be given to those who obey the Law, then faith means nothing and God’s promise is worthless. 15The Law brings down God’s anger; but where there is no law, there is no disobeying of the law. 16And so the promise was based on faith, in order that the promise should be guaranteed as God’s free gift to all of Abraham’s descendants—not just to those who obey the Law, but also to those who believe as Abraham did. For Abraham is the spiritual father of us all; 17as the scripture says, “I have made you father of many nations.” So the promise is good in the sight of God, in whom Abraham believed—the God who brings the dead to life and whose command brings into being what did not exist.
Paul wants the readers of his letter to know that God can make people righteous 'apart from the law'. Abraham was the father of Israel, he lived before the people of Israel were taken into exile in Egypt - before Moses gave the law. Abraham simply put his faith and trust in the character and love of God.
Lord I put my trust in you. You are a good and loving King, my saviour and Lord.