Avenge not (μη εκδικουντες). Independent participle again of late verb εκδικεω from εκδικος, exacting justice (Romans 13:4). See already Luke 18:5; 2. Corinthians 10:6.

But give place unto wrath (αλλα δοτε τοπον τη οργη). Second aorist active imperative of διδωμ, to give. "Give room for the (note article as in Romans 5:9; 1. Thessalonians 2:16) wrath" of God instead of taking vengeance in your own hands. See Ephesians 4:27 for διδοτε τοπον. Paul quotes Deuteronomy 32:35 (the Hebrew rather than the LXX). So have Hebrews 10:30 and the Targum of Onkelos, but the relation between them and Paul we cannot tell. Socrates and Epictetus condemned personal vindictiveness as Paul does here.

I will recompense (ανταποδωσω). Future active of the double compound verb quoted also in Romans 11:35.