16 So let your light shine before men, that they may see your good works, and glorify your Father who is in heaven.
Hilary: He instructs the Apostles to shine with such a light, that in the admiration of their work God may be praised.
He means not that we should seek glory of men, but that though we conceal it, our work may shine forth in honour of God to those among whom we live.
Pseudo-Chrysostom: That is, teaching with so pure a light, that men may not only hear your words, but see your works, that those whom as lamps ye have enlightened by the word, as salt ye may season by your example. For by those teachers who do as well as teach, God is magnified; for the discipline of the master is seen in the behavior of the family.
Augustine: Had He only said, “That they may see your good works,” He would have seemed to have set up as an end to be sought the praised of men, which the hypocrites desire; but by adding, “and glorify your Father,” he teaches that we should not seek as an end to please men with our good works, but referring all to the glory of God, therefore seek to please men, that in that God may be glorified.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. I (London: Rivington, 1842).