Psalm 73
Book Three opens with an honest crisis of faith. Asaph nearly slipped, envying the arrogant who seem to have it easy, and thought "in vain I have kept my heart pure." He doesn't rush past it, and he even admits he was "a brute beast" in his bitterness. The turn comes in God's sanctuary, in worship, not in an argument. Then it opens out: You hold my right hand, and there's no one in heaven or earth I want but You.
"My flesh and my heart may fail, but God is the strength of my heart and my portion forever." (Psalm 73:26)
Versions/Hebrew: "the strength of my heart" in 73:26 is tzur levavi [6697], "the rock of my heart"; YLT keeps "The rock of my heart." "Portion" (cheleq [2506]) is the word for a share of the land; God Himself is Asaph's inheritance.