Albert Barnes Commentary Psalms 35:27

"Let them shout for joy, and be glad, that favor my righteous cause: Yea, let them say continually, Jehovah be magnified, Who hath pleasure in the prosperity of his servant." — Psalms 35:27 (ASV)

Let them shout for joy — That is, let me be delivered; let my friends see that God is on my side, and that they have occasion to rejoice in his merciful interposition on my behalf.

That favor my righteous cause — Margin, as in Hebrew, “my righteousness.” The reference is to those who considered his cause a just one, and who were his friends.

Yea, let them say continually — Let this be a constant subject of grateful reflection—a perpetual source of joy to them—that God has interposed on my behalf, and has shown that my cause was a just one.

Let the Lord be magnified — Be regarded as great, exalted, glorious. Let the effect be to elevate their conceptions of the character of God by the fact that he has thus interposed in a righteous cause, and has shown that he is the friend of the wronged and the oppressed.

Which hath pleasure in the prosperity of his servant — Who delights to make his friends prosperous and happy. Let them see that this is the character of God, and let them thus be led to rejoice in him evermore.