"Let Your mercy, O Lord, be upon us, according as we have hoped in You" [Psalm 33:22]: let Your mercy, O Lord, be upon us; for hope confounds not, because we have hoped in You.
Then when he says, "Let your mercy be upon us," the effect of prayer is set forth; for prayer is the interpreter of hope, and therefore it follows upon hope. And although every particular benefit is from divine mercy, two are especially from it. The first is the benefit of the incarnation: Lk. 1: "Through the tender mercy of our God," and so on. "Let your mercy be upon us," namely, that you may take on flesh and free us; "upon us," that is, above our merits. The other benefit is that of salvation; and this is "upon us," because "not by the works of justice that we have done, but according to his mercy he saved us," Tit. 3: "Even as we have hoped in you," because "no one has hoped in the Lord and been confounded," Sir. 2.