Psalms 149:6

The Israel of God are here represented triumphing over their enemies, which is both the matter of their praise (let them give to God the glory of those triumphs) and the recompence of their praise; those that are truly thankful to God for their tranquillity shall be blessed with victory. Or it may be taken as a further expression of their praise (Psa 149:6): let the high praises of God be in their mouth, and then, in a holy zeal for his honour, let them take a two-edged sword in their hand, to fight his battles against the enemies of his kingdom. Now this may be applied, 1. To the many victories which God blessed his people Israel with over the nations of Canaan and other nations that were devoted to destruction. These began in Moses and Joshua, who, when they taught Israel the high praises of the Lord, did withal put a two-edged sword in their hand; David did so too, for, as he was the sweet singer of Israel, so he was the captain of their hosts, and taught the children of Judah the use of the bow (Sa2 1:18), taught their hands to war, as God had taught his. Thus he and they went on victoriously, fighting the Lord's battles, and avenging Israel's quarrels on those that had oppressed them; then they executed vengeance upon the heathen (the Philistines, Moabites, Ammonites, and others, Sa2 8:1, etc.

— Matthew Henry's Concise Commentary (public domain)

high praises--or, "deeds." They shall go forth as religious warriors, as once religious laborers (Neh 4:17).

— Jamieson-Fausset-Brown Commentary (public domain)