'Promised' in the Bible

which He promised beforehand through His prophets in the sacred Scriptures—

(as it is written [in Scripture], “I have made you a father of many nations”) in the sight of Him in whom he believed, that is, God who gives life to the dead and calls into being that which does not exist.

In hope against hope Abraham believed that he would become a father of many nations, as he had been promised [by God]: “So [numberless] shall your descendants be.”

being fully convinced that God had the power to do what He had promised.