Romans 4:11

and he received the sign of circumcision, as a seal of the justification by that faith, which the uncircumcised have: that he might be the father of all those who believe, tho' they are uncircumcised, that it might be accounted to them also for righteousness:

Acts 7:8

at length he gave him the covenant of circumcision: accordingly Abraham circumcised his son Isaac eight days after he was born, Isaac was father of Jacob, who was father of the twelve patriarchs.

Treasury of Scripture Knowledge

Summary

And ye shall circumcise the flesh of your foreskin; and it shall be a token of the covenant betwixt me and you.

Bible References

A token

Acts 7:8
at length he gave him the covenant of circumcision: accordingly Abraham circumcised his son Isaac eight days after he was born, Isaac was father of Jacob, who was father of the twelve patriarchs.
Romans 4:11
and he received the sign of circumcision, as a seal of the justification by that faith, which the uncircumcised have: that he might be the father of all those who believe, tho' they are uncircumcised, that it might be accounted to them also for righteousness:
Acts 7:8
at length he gave him the covenant of circumcision: accordingly Abraham circumcised his son Isaac eight days after he was born, Isaac was father of Jacob, who was father of the twelve patriarchs.
Romans 4:11
and he received the sign of circumcision, as a seal of the justification by that faith, which the uncircumcised have: that he might be the father of all those who believe, tho' they are uncircumcised, that it might be accounted to them also for righteousness: