Have mercy upon me, O Lord! The consideration of God's mercies in the past, and especially in the recent deliverance, leads the psalmist to implore a continuance of his mercies in the future. He is not yet free from troubles.
There are still enemies who afflict and threaten him—"heathen" who seek to "prevail" against him (Psalms 9:19, Psalms 9:20), and perhaps already domestic enemies, especially the "sons of Zeruiah," causing him anxiety.
Consider my trouble which I suffer of them that hate me; literally, my trouble (or, my affliction) from my haters. Psalms 9:17, Psalms 9:19, Psalms 9:20 show that the heathen are especially intended (see 2 Samuel 10:15-19).
Thou that liftest me up from the gates of death; i.e. "Thou that continually (or, habitually) art my Support in the extremity of peril," "lifting me up" even from the very "gates of death." (For other mentions of "the gates of death," see Job 38:17; Psalms 107:18.
) Classical writers speak of "the gates of darkness" ( σκότου πύλας) in almost the same sense (Eurip; 'Hec.,' 1. 1).