ISB ~ Galatians 3 v15

will:The term means “testament” or “will” in secular Greek usage but “covenant” in biblical Greek usage. Despite the RSV translation, the biblical sense of “covenant” is probably intended here, since (1)Paul uses the term this way in his other writings (Rom 9:4; 11:27; 2 Cor 3:6, 14; Eph 2:12), (2) he uses it this way elsewhere in Galatians (3:17; 4:24), and (3) it is a known fact that a will in Greco-Roman antiquity could be altered or even annulled after the death of the testator who drafted it, which is the very point Paul denies in this verse. For a similar translation issue in Hebrews, see essay: Will or Covenant? at Heb 9.