When the believer is suffering wasting disease and impending death, despairing loneliness, emotional turmoil, spiritual distress, and threatening enemies he turns to God in prayer begging to be heard and answered quickly.
Part of the appeal includes a description of his terrible condition, his gloating enemies and his mourning for sin. A part of that descriptive appeal includes the complaint that God his Creator is eternal, not subject to death or to change, and he is not eternal and about to die prematurely. His God is merciful and He will keep His promises to restore His people, so he prays that the Lord would restore him, too.
Part of the appeal is simply to the character of the Eternal God: He makes promises, He answers prayer, He hears the cries of the destitute and dying, He overcomes enemies, and He will create new people who will praise Him in future days. Let Him record for the next generation the salvation He brought today.
We don’t need to remind Him of our need and of His character, but we have the privilege of enjoying our faith relationship with an unseen but ever present Lord. We need the prayer response to His grace to remind ourselves.