Psalm 145:12 (ESV)

12 to make known to the children of man your mighty deeds, and the glorious splendor of your kingdom.

The sentence that starts in Psalm 145:11 continues in Psalm 145:12. The purpose or the direction of the witnessing by God’s people is that they, by their witness, proclaim the mighty deeds of the Lord (see Psalm 145:6) to all peoples.