John Chrysostom

"And when this Epistle hath been read among you, cause that it be read also in the church of the Laodiceans." I suppose there are some of the things therein written, which it was needful that those also should hear. And they would have the greater advantage of recognizing their own errors in the charges brought against others. "And that ye also read the Epistle from Laodicea." Some say that this is not Paul's to them, but theirs to Paul, for he said not that to the Laodiceans, but that written "from Laodicea."

Homily on Colossians 12 ↗

Theophylact of Ohrid

It seems to me that something was written here that the Laodiceans also needed to hear; and they, in turn, needed to learn what was written in that epistle. There is much more benefit when, from a rebuke directed against others, they learn of their own shortcomings. What then was this epistle from Laodicea? The First Epistle to Timothy: it was written from Laodicea. Some, however, say that it was an epistle that the Laodiceans were sending to Paul. But I do not know what they could have borrowed from it for their own correction.

Commentary on Colossians ↗

Thomas Aquinas

We can see from what he says, see that you read also the letter from Laodicea, that Paul wrote other letters: the one to the Laodiceans mentioned here, and another to the Corinthians, besides the first and second, because in 1 Corinthians (5:9) he says: "I wrote to you in my letter not to associate with immoral men." There are two reasons why they are not in the canon: either there was some doubt about their authority, because they were possibly distorted, and had been destroyed in the churches, or because they contained nothing …

Commentary on Colossians ↗