Quotation
The promised sojourn and deliverance
Stephen repeats God's words to Abraham that his descendants would live as strangers, suffer enslavement for four hundred years, and afterward be delivered when God judged the enslaving nation.
Acts 7:5–7
He gave him no inheritance here, not even a foot of ground. But God promised to give possession of the land to Abraham and his descendants, even though he did not yet have a child. God told him that his descendants would be foreigners in a strange land, and that they would be enslaved and mistreated four hundred years. ‘But I will punish the nation that enslaves them,’ God said, ‘and afterward they will come forth and worship Me in this place.’
Genesis 15:13-14 foretells a four-hundred-year sojourn, enslavement, God's judgment on the nation, and the descendants' departure; Acts 7:5-7 recounts the same promise in Stephen's address.
Quotation
Abraham believed God
Paul quotes Genesis to show that Abraham believed God and was counted righteous.
Galatians 3:6–8
So also, “Abraham believed God, and it was credited to him as righteousness.” Understand, then, that those who have faith are sons of Abraham. The Scripture foresaw that God would justify the Gentiles by faith, and foretold the gospel to Abraham: “All nations will be blessed through you.”
Genesis 15:6 says that Abram believed the LORD and that it was credited to him as righteousness. Galatians 3:6 repeats these words while Paul speaks about people who have faith.
Quotation
Abraham believes God's promise
Paul uses God's promise of numerous offspring and Abraham's faith being credited as righteousness to explain that righteousness is credited through faith rather than earned by works.
Romans 4:1–5
What then shall we say that Abraham, our forefather, has discovered? If Abraham was indeed justified by works, he had something to boast about, but not before God. For what does the Scripture say? “Abraham believed God, and it was credited to him as righteousness.” Now the wages of the worker are not credited as a gift, but as an obligation. However, to the one who does not work, but believes in Him who justifies the wicked, his faith is credited as righteousness.
Romans 4:18
Against all hope, Abraham in hope believed and so became the father of many nations, just as he had been told, “So shall your offspring be.”
Romans 4:22–24
This is why “it was credited to him as righteousness.” Now the words “it was credited to him” were written not only for Abraham, but also for us, to whom righteousness will be credited—for us who believe in Him who raised Jesus our Lord from the dead.
Romans 4:3 asks what Scripture says and quotes Genesis 15:6; Romans 4:18 quotes the promise in Genesis 15:5; and Romans 4:22-24 returns to the credited-righteousness wording and applies it to those who believe in the God who raised Jesus.