28 “The Lord has said, Out of Basan I will be turned”: or, as some copies have, “Out of Basan I will turn.” For He turns that we may be safe, of whom above has been said, “God of our healths, and God of saving men.” For to Him elsewhere also is said, “O God of virtues, turn Thou us, and show Your face, and safe we shall be.” Also in another place, “Turn us, O God of our healths.” But he has said, “Out of Basan I will turn.” Basan is interpreted confusion. What is then, I will turn out of confusion, but that there is confounded because of his sins, he that is praying of the mercy of God that they may be put away?
Thence it is that the Publican dared not even to lift up his eyes to Heaven: so, on considering himself, was he confounded; but he went down justified, because “the Lord has said, Out of Basan I will turn.” Basan is also interpreted drought: and rightly the Lord is understood to turn out of drought, that is, out of scarcity. For they that think themselves to be in plenty, though they be famished; and full, though they be altogether empty; are not turned....“I will turn unto the deep of the sea.”
If, “I will turn,” why, “unto the deep of the sea”? Unto Himself indeed the Lord turns, when savingly He turns, and He is not surely Himself the deep of the sea. Does perchance the Latin expression deceive us, and has there been put “unto the deep,” for a translation of what signifies “deeply”? For He does not turn Himself: but He turns those that in the deep of this world lie sunk down with the weight of sins, in that place where one that is turned says, “From the depths I have cried to You, O Lord.” But if it is not, “I will turn,” but, “I will be turned unto the deep of the sea;” our Lord is understood to have said, how by His own mercy He was turned even unto the deep of the sea, to deliver even those that were sinners in most desperate case.
Though in one Greek copy I have found, not, “unto the deep,” but “in the depths,” that is, ἐ ν βυθοῖς: which strengthens the former sense, because even there God turns to Himself men crying from the depths. And even if He be understood Himself there to be turned, to deliver such sort also, it is not beside the purpose: and so then He turns, or else to deliver them is so turned, that His foot is stained in blood. Which to the Lord Himself the Prophet speaks: “That Your foot may be stained in blood”: that is, in order that they themselves who are turned to You, or to deliver whom You are turned, though in the deep of the sea by the burden of iniquity they may have been sunk, may make so great proficiency by Your Grace (for where there has abounded sin, there has superabounded grace), that they may become Your foot among Your members, to preach Your Gospel, and for Your name's sake drawing out a long martyrdom, even unto blood they may contend.
For thus, as I judge, more meetly is perceived His foot stained in blood.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)