Psalm 21:7 New English Translation

⁷For the king trusts^[a] in the Lord,
and because of the Most High’s^[b] faithfulness he is not shaken.^[c]

Psalm 21:7 tn The active participle draws attention to the ongoing nature of the action.
Psalm 21:7 sn The divine title “Most High” (עֶלְיוֹן, ʿelyon) pictures God as the exalted ruler of the universe who vindicates the innocent and judges the wicked. Note the focus of vv. 8-12 and see Ps 47:2.
Psalm 21:7 tn Another option is to translate the imperfect verbal form as future, “he will not be shaken” (cf. NRSV “he shall not be moved”). Even if one chooses this option, the future tense must be understood in a generalizing sense.

New English Translation (NET)