Let all mine enemies be ashamed and sore vexed: let them return and be ashamed suddenly.
Let all ... - or, 'All mine enemies shall be ashamed, etc. But the Chaldaic, Vulgate, Arabic, Syriac, and Septuagint support the English version (Hengstenberg).
Sore vexed - literally, 'terrified;' as also in Psalms 6:2-3, to which he refers here. The terror is transferred, in righteous retribution, from David to those who had caused it, to him.
Let them return - or, 'they shall return.' In either translation he confidently anticipates this result from his prayer. They who were advancing to attack him suddenly, in terror, fall back and "return," because God, in answer to his prayer (Psalms 6:4), has returned to him. The return of Yahweh is the cause; their return from Him effect.