How many are the days of Your servant? When will You execute judgment on those who persecute me?
NASB95
How long must your servant endure? When will you judge those who persecute me?
ESV
How many are the days of thy servant? when wilt thou execute judgment on them that persecute me?
KJV

"How many are the days of your servant?" I cannot hope to live long in such a condition; you must come speedily to my rescue or I shall die. Shall all my short life be consumed in such destroying sorrows? The brevity of life is a good argument against the length of an affliction. Lord, since I am to live so short a time, be pleased to shorten my sorrow also.

Perhaps the Psalmist means that his days seemed too many since they were spent in such distress. He half wished that they were ended, and therefore he asked in trouble, "How many are the days of your servant?" Long life now seemed a calamity rather than a blessing. Like a hired servant, he had a certain term to serve, and he would not complain of what he had to bear; but still the time seemed long because his griefs were so heavy. No one knows the appointed number of our days except the Lord, and therefore to him the appeal is made that he would not prolong them beyond his servant's strength. It cannot be the Lord's mind that his own servant should always be treated so unjustly; there must be an end to it; when would it be?

"When will you execute judgment on them that persecute me?" He had placed his case in the Lord's hands, and he prayed that sentence might be given and put into execution. He desired nothing but justice, that his character might be cleared and his persecutors silenced. He knew that God would certainly avenge his own elect, but the day of rescue tarried, the hours dragged heavily along, and the persecuted one cried day and night for deliverance.