A.T. Robertson Commentary Ephesians 4:8

"Wherefore he saith, When he ascended on high, he led captivity captive, And gave gifts unto men." — Ephesians 4:8 (ASV)

Wherefore he saith (διο λεγε). As a confirmation of what Paul has said. No subject is expressed in the Greek and commentators argue whether it should be ο θεος (God) or η γραφη (Scripture). But it comes to God after all. See Ac 2:17. The quotation is from Ps 68:18, a Messianic Psalm of victory which Paul adapts and interprets for Christ's triumph over death.

He led captivity captive (ηιχμαλωτευσεν αιχμαλωσιαν). Cognate accusative of αιχμαλωσιαν, late word, in N.T. only here and Re 13:10. The verb also (αιχμαλωτευω) is from the old word αιχμαλωτος, captive in war (in N.T. only in Lu 4:18), in LXX and only here in N.T.