Though they plan evil against you, though they devise mischief, they will not succeed.
PSALM 21. This psalm contains a public and solemn thanksgiving for the prosperous and happy condition of the king. Its subject is almost the same with that of the preceding. “What was anticipated in the preceding psalm, the present poem appears to celebrate as having been achieved.” — Drake’s Harp of Judah.
Commenting on Psalm 21:1-13
"For they intended evil against thee." God takes notice of intentions. He who would but could not is as guilty as he who did. Christ's church and cause are not only attacked by those who do not understand it, but there are many who have the light and yet hate it.
The psalmist, having taught his people to look back with joy and praise on what God had done for him and them, here teaches them to look forward with faith, and hope, and prayer, upon what God would further do for them: The king rejoices in God (Psa 21:1), and therefore we will be thankful; the king trusteth in God (Psa 21:7), therefore will we be encouraged.
Commenting on Psalm 21:7-13