Theophylact of Ohrid

Nor should you think that because Christ in His love for mankind accepts mercy shown to others as something offered to Himself, that we should overlook God and only practice almsgiving. For if this were so, we ought then to steal from the temples and use what is stolen for almsgiving. …

Commentary on Matthew ↗

Jerome

Here a question arises how the Lord should have said elsewhere to His disciples, Lo, I am with you always, even to the end of the world; but here, Me ye shall not have always. (Matt. 28:20.) I suppose that in this place He speaks of His bodily presence, which shall not be with them after the resurrection in daily intercourse and friendship, as it is now.

Catena Aurea by Aquinas ↗

Thomas Aquinas

For the poor you have always with you etc. Here is set forth the response to their objection, because they were saying that it could have been given to the poor. But me you have not always. This is true according to bodily presence, but he will always be present according to spiritual presence. Hence he says below, at the end, 28:20: behold I am with you all days, even to the consummation of the world.

Commentary on Matthew ↗

Remigius of Rheims

For the poor ye have ever with you. The Lord shows in these words as of set purpose, that they were not to be blamed who ministered of their substance to Him while He dwelt in a mortal body; forasmuch as the poor were ever in the Church, to whom the believers might do good whensoever they would, but He would abide in the body with them but a very short time; whence it follows, But me ye shall not have always. …

Catena Aurea by Aquinas ↗