Augustine of Hippo

"I will confess unto You, O Lord, with my whole heart" [Psalm 9:1]. He does not, with a whole heart, confess unto God, who doubts of His Providence in any particular: but he who sees already the hidden things of the wisdom of God, how great is His invisible reward, who says, "We rejoice in tribulations;" [Romans 5:3] and how all torments, which are inflicted on the body, are either for the exercising of those that are converted to God, or for warning that they be converted, or for just preparation of the obdurate unto their last …

Exposition on Psalm 9 ↗

Jerome

Joshua the son of Nun was fighting in the desert, and as Moses prayed he kept prevailing: the one man fought, the other by his prayer conquered. So too do I, according to that which is written, 'Open your mouth, and I will fill it': I indeed seem to be the one speaking, but there are others by whose prayers I speak. The ninth psalm, which has been sung by you to the Lord, is great in its verses, great in its mysteries. Since, then, we cannot discuss everything, it is enough for the moment to speak about the title. …

Homily 4, on Psalm 9 ↗

Thomas Aquinas

Above, in the preceding Psalm, he gave thanks for benefits bestowed upon the whole human race; but in this Psalm he specifically gives thanks for the benefit bestowed upon himself in the destruction of his enemies. And this is clear from the title according to Jerome, which is as follows: "To the victor, for the death of the son, a canticle of David," etc. And it touches upon the history of 2 Sam. 18 and 19, that when Absalom died, he recovered the kingdom; and for this benefit he composed this Psalm. …

Exposition on the Psalms of David ↗