John Calvin Commentary Psalms 119:84

"How many are the days of thy servant? When wilt thou execute judgment on them that persecute me?" — Psalms 119:84 (ASV)

How many are the days of thy servant? etc. Some interpret these two clauses separately, as if the first were a general complaint about the brevity of human life, such as is found in other psalms and more frequently in the book of Job. Then, in their opinion, a special prayer of the Psalmist follows, asking that God would take vengeance on his enemies.

But I prefer to join the two clauses together and limit both to David’s afflictions, as if he were saying: "Lord, how long have you determined to abandon your servant to the will of the ungodly? When will you set yourself in opposition to their cruelty and outrage, in order to take vengeance on them?"

The Scriptures often use the word days in this sense; for example, the days of Egypt (Ezekiel 30:9), the days of Babylon, and the days of Jerusalem (Psalms 137:7). This word, in other places, is called the day of visitation (Isaiah 10:3). The use of the plural number denotes a specific, determined portion of time, which in other places is compared to the days of an hireling (Job 14:6; Isaiah 16:14).

The Psalmist does not, then, lament in general human life, but he complains that the time of his state of warfare in this world had been too long extended. Therefore, he naturally desires for it to be brought to an end.

When reasoning earnestly with God about his trouble, he does not do so obstinately or with a murmuring spirit. Instead, while asking how long it will be necessary for him to suffer, he humbly prays that God would not delay to help him.

As for urging God through prayer to execute vengeance, we have seen elsewhere in what sense it was permissible for him to make such a request—namely, because the vengeance he desired to see was of a kind properly suitable to God. It is certain that he had put aside all corrupt desires of the flesh, so that he might, with a pure and undisturbed zeal, desire God’s judgment. However, in this passage, he only wishes in general to be delivered by God's hand from the wrongs inflicted on him, without condemning his adversaries to perdition, for he was fully content, provided God appeared to defend him.