Albert Barnes Commentary Psalms 21:11

"For they intended evil against thee; They conceived a device which they are not able to perform." — Psalms 21:11 (ASV)

For they intended evil against you - literally, “They stretched out evil.” The idea seems to be derived from “stretching out” or laying snares, nets, or traps for the purpose of capturing wild animals. That is, they formed a plan or purpose to bring evil upon God and His cause, just as the hunter or fowler forms a purpose or plan to capture wild animals or birds.

This is not merely a purpose in the mind, as our word “intended” might seem to imply. It suggests that arrangements had been made, or that a scheme had been formed, to injure the cause of God—that is, through the person referred to in the psalm.

The purposes of the wicked against religion are usually much more than a mere “intention.” Such an intention is accompanied by a scheme or plan in their minds by which the act may be accomplished.

The evil referred to here was that of resisting or overpowering him who was engaged in the cause of God, or whom God had appointed to administer His laws.

They imagined a mischievous device - They thought, or they purposed. The word translated “mischievous device,” מזמה (m'zimmâh), properly means “counsel, purpose; then prudence, sagacity;” and then, in a bad sense, “machination, device, trick” (Gesenius, Lexicon). Compare Proverbs 12:2; Proverbs 14:17; Proverbs 24:8.

Which they are not able to perform - literally, “they could not;” that is, they did not have the power to accomplish it or to carry out their purpose. Their purpose was plain; their guilt was therefore clear; but they were prevented from executing their design. Many such designs are prevented from being carried out due to a lack of power. If all the devices and desires of the wicked were accomplished, righteousness would soon cease on the earth, religion and virtue would come to an end, and even God would cease to occupy the throne.