Albert Barnes Commentary Psalms 119:88

"Quicken me after thy lovingkindness; So shall I observe the testimony of thy mouth." — Psalms 119:88 (ASV)

Quicken me - Cause me to live; revive me. See (Psalms 71:20), note; (Ephesians 2:1), note. Compare (Psalms 80:18); (Romans 8:11); (1 Peter 3:18); (John 6:63).

After Your loving-kindness - Your mercy; Your grace; Your compassion. That is, let the measure of the grace given to me be Your own benevolent nature, and not what I deserve. That is all I ask; that is all I could desire.

So I will keep the testimony of Your mouth - Which proceeds out of Your mouth. His hope of being able to keep it was founded on the grace and mercy which he implored God to bestow upon him.