19 But this mountain he calls the “mountain of God, a mountain fruitful, a mountain full of curds”, or “a mountain fat.” But here what else would he call fat but fruitful? For there is also a mountain called by that name, that is to say, Selmon. But what mountain ought we to understand by “the mountain of God, a mountain fruitful, a mountain full of curds,” but the same Lord Christ? Of whom also another Prophet says, “There shall be manifest in the last times the mountain of the Lord prepared on the top of the mountains”? He is Himself the “Mountain full of curds,” because of the babes to be fed with grace as though it were with milk; a mountain rich to strengthen and enrich them by the excellence of the gifts; for even the milk itself whence curd is made, in a wonderful manner signifies grace; for it flows out of the overflowing of the mother's bowels, and of a sweet compassion unto babes freely it is poured forth.
But in the Greek the case is doubtful, whether it be the nominative or the accusative: for in that language mountain is of the neuter gender, not of the masculine: therefore some Latin translators have not translated it, “unto the Mountain of God,” but, “the Mountain of God.” But I think, “unto Selmon the Mountain of God,” is better, that is, “unto” the Mountain of God which is called Selmon: according to the interpretation which, as we best could, we have explained above.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)