Gerhard (Good works, § 33): James 2:21: “Abraham was justified by works,” that is, he was shown to be righteous by them, as Thomas and the Glossa correctly explain.
Thomas (on James 2): Sed videtur falsum quod dicit, nonne ex operibus justificatus est? Quia Rom. 4 probat apostolus, quod Abraham ex fide justificatus est, non ex operibus: et ibidem dicitur, credidit Abraham Deo, et reputatum est ei ad justitiam: ibi: Glossa Augustini, non ex operibus justificatus est, sed ex fide. Responsio. Apostolus et Augustinus loquuntur de operibus praecedentibus fidem, scilicet operibus legalibus, ut patet ibidem, ex quibus nullus plene justificatus est: hic autem loquitur de operibus sequentibus fidem, quae dicuntur justificare non secundum quod justificatio dicitur justitiae infusio, sed secundum quod dicitur justitiae exercitatio, vel ostensio, vel consummatio.
The Glossa (https://archive.thulb.uni-jena.de/ufb/rsc/viewer/ufb_derivate_00000066/Mon-typ-2-00011_521.tif) is even clearer, saying that Abraham became righteous through faith alone, and that the works that follow faith are a testimony to the righteousness of faith.
Ambrose (Sunday Sermons, 91b): “The Lord our God therefore tempers His justice with His mercy. For who among us could stand without the divine mercy? What could we do that would be worthy of heavenly rewards? Who amongst us could so rise up in this body of ours so as to uplift his own soul to where it might for ever cleave to Christ? How far would the good men do avail them, that this corruptible body might put on incorruption, and this mortal put on immortality (1 Cor. 15:53)? By what labor of ours, by what sufferings, could we wash clean our own sins? The sufferings of this time are not be compared to the glory to come (Rom. 8:18). It is not therefore in accordance with our merits that the nature of the divine decrees concerning man reveals itself, but in accordance with the mercy of God, to Whom be honour and glory for ever and ever. Amen.”
Ambrose, On 1 Corinthians 1: “Grace is given in Christ because it has been established by God that whoever believes in Christ is saved apart from work, by faith alone, freely receiving the forgiveness of sins.” Preface to his commentary on Galatians: “Faith alone is sufficient for salvation.”
Pelikan, Growth of Medieval Theology, 27-29