Numbers 23:19 declares God does not lie or change His word — directly opposing the psalmist's doubt that God's promise might fail.

Jeremiah 15:18 asks if God will be like a liar or failing waters — nearly identical to the psalmist's question about mercy and promise failing.

Romans 9:6 affirms God's word has not failed — a direct answer to the psalmist's doubt about promise failing.

Lamentations 3:22 declares God's compassions never fail — directly refuting the psalmist's question 'Is his mercy clean gone forever?'