Albert Barnes Commentary Psalms 119:122

"Be surety for thy servant for good: Let not the proud oppress me." — Psalms 119:122 (ASV)

Be surety for your servant for good — regarding the meaning of the word rendered here as “be surety,” see the notes on Job 17:3 and Isaiah 38:14, in both of which places the same Hebrew word occurs. In Isaiah it is rendered “undertake for me”.

The word properly means “to mix, to mingle”; hence, to braid, to interweave; then, to exchange, to barter. Then it means to mix or intermingle interests; to unite ourselves with others so that their interests become our own; and hence, to take someone under our protection, to become answerable for them, or to be a surety for them: just as when one person endorses a note for another, he mingles his own interest, reputation, and means with those of that other person.

So Christ becomes the security or surety—ἔγγυος enguos—of His people (Hebrews 7:22).

The prayer here is that God would, so to speak, mix or mingle His cause and that of the psalmist together, and that He would then protect the common cause as His own; or, that He would become a “pledge” or “surety” for the safety of the psalmist. This now, through the Mediator, we have a right to ask from God; and when God makes our cause His own, we must be safe.

Let not the proud oppress me — see the notes on Psalm 119:51. Let them not triumph over me and crush me.