Old Testament

The Book of Exodus:
Chapter 12:21-28

Then Moses called for all the elders of Israel and said to them, "Pick out and take lambs for yourselves according to your families, and kill the Passover lamb. And you shall take a bunch of hyssop, dip it in the blood that is in the basin, and strike the lintel and the two doorposts with the blood that is in the basin. And none of you shall go out of the door of his house until morning. For the Lord will pass through to strike the Egyptians; and when He sees the blood on the lintel and on the two doorposts, the Lord will pass over the door and not allow the destroyer to come into your houses to strike you. And you shall observe this thing as an ordinance for you and your sons forever. It will come to pass when you come to the land which the Lord will give you, just as He promised, that you shall keep this service. And it shall be, when your children say to you, 'What do you mean by this service?' that you shall say, 'It is the Passover sacrifice of the Lord, who passed over the houses of the children of Israel in Egypt when He struck the Egyptians and delivered our households.' " So the people bowed their heads and worshiped. Then the children of Israel went away and did so; just as the Lord had commanded Moses and Aaron, so they did.

New Testament

The Epistle of Paul the Apostle to the Romans:
Chapter 4:1-9-12

What then shall we say that Abraham our father has found according to the flesh? For if Abraham was justified by works, he has something to boast about, but not before God. For what does the Scripture say? "Abraham believed God, and it was accounted to him for righteousness." Now to him who works, the wages are not counted as grace but as debt. But to him who does not work but believes on Him who justifies the ungodly, his faith is accounted for righteousness, just as David also describes the blessedness of the man to whom God imputes righteousness apart from works: "Blessed are those whose lawless deeds are forgiven, And whose sins are covered; Blessed is the man to whom the Lord shall not impute sin."

Does this blessedness then come upon the circumcised only, or upon the uncircumcised also? For we say that faith was accounted to Abraham for righteousness.
How then was it accounted? While he was circumcised, or uncircumcised? Not while circumcised, but while uncircumcised. And he received the sign of circumcision, a seal of the righteousness of the faith which he had while still uncircumcised, that he might be the father of all those who believe, though they are uncircumcised, that righteousness might be imputed to them also, and the father of circumcision to those who not only are of the circumcision, but who also walk in the steps of the faith which our father Abraham had while still uncircumcised.