Genesis 15: 5 And he brought him forth abroad, and said, Look now toward heaven, and tell the stars, if thou be able to number them: and he said unto him, So shall thy seed be.
At the time when our first passage was taking place, Abraham, and his wife Sarah were well into their golden years, yet, when the statement of promise came down to him from God, Abraham believed. It was not a one-time belief that is here mentioned, he was in the habit of believing, and because of this, the promise of God, and the righteousness of Christ could be imputed, and imparted to him.
Abraham, like all of us was not naturally biased to righteousness from birth, for anyone to conclude that he may have had an advantage or a head start from the womb. Like any other descendent of Adam, Abraham had a natural bent towards evil, and because of this, the righteousness of Christ would have to be given, as a gift to him, just like it has to be with every other person.
It was not something that Abraham would do that gave Abraham confidence in the promise; it was something that only God could do, and Abraham believed that God could be depended on to do the impossible. Thus, three prominent features of this exchange between God and Abraham come to light, as it pertains to righteousness by faith.
Genesis 15:6 And he believed in the Lord; and he counted it to him for righteousness.
May God add His blessing to the study of His word. “Good night” and God bless!