In anticipation of God"s help, the writer promised to praise Him with stringed instruments, as well as vocally. The title "Holy One of Israel" ( Psalm 71:22) is common in Isaiah but rare in the Psalm , occurring only three times (cf. Psalm 78:41; Psalm 89:18). In conclusion, the psalmist spoke of his accusers" humiliation as already present, even though that is what he was requesting. This is probably another instance of expressing confidence that something would happen by describing it as having already taken place. [source][source][source]
When people have trusted in God over a lifetime and have seen Him deliver them from many trials, it becomes easier for them to trust Him in the present. Just as continual unbelief makes faith more difficult, continual trust makes unbelief more difficult. [source][source][source]