Acts 7:8

The covenant of circumcision

(διαθηκην περιτομης). A covenant marked by (genitive) circumcision (no article) of which circumcision is the sign (Romans 4:11) as set forth in Genesis 17:9-14. In the ancient Greek διαθηκη was usually will (Latin, testamentum) and συνθηκη was used for covenant (συν, together, rather than δια, between). But the LXX and the N.T. use διαθηκη for covenant (will in Hebrews 9:15) as Lightfoot on Galatians 3:16 says: "The LXX translation and New Testament writers probably preferred διαθηκη as better expressing thefree grace

of God than συνθηκη."And so

(κα ουτως). After the covenant was made and as a sign and seal of it.