en_tn_condensed/psa/086/013.md

For great is your covenant faithfulness toward me

The abstract noun "faithfulness" can be stated as an adjective. Alternate translation: "For you are very faithful to me because of your covenant" (See: rc://en/ta/man/translate/figs-abstractnouns)

you have rescued my life from the depths of Sheol

This does not mean God brought him back to life after he died. It means God saved him when he was about to die.