Plead my cause … - Undertake my cause, as an advocate does. See the notes at Psalm 35:1.
Quicken me … - Give me life. See the notes at Psalm 119:25.
SDA Bible Commentary (limited)
Volume 1-7
154. Plead my cause. The psalmist and his enemies are represented as on trial. David is asking God to be his advocate and to take his side in the controversy.