John Chrysostom

And whereas Mark saith, He took the three disciples, and so doth Luke; our evangelist merely saith, "the disciples." Wherefore then did He not take with Him Matthew, though he had but just come unto Him? To bring him to a more earnest longing, and because he was yet rather in an imperfect state. For to this intent doth He honor those, that these may grow such as those are. But for him it sufficed for the present, to see what befell the woman with the issue of blood, and to be honored by His table, and by His partaking of his salt. …

Homily on the Gospel of Matthew 31 ↗

Thomas Aquinas

And Jesus rose and followed him. He rose, namely, from the meal. Here we have evidence of Christ's mercy, because after the request he went at once, as it says in Isaiah (30:19): "As soon as he hears your cry, he will answer you." Likewise, he gives an example of solicitude to prelates, that they should be solicitous about helping sinners quickly. He also gives an example of obedience, because he took disciples with him: "Obey your prelates" (Heb 13:17). But he did not bring Matthew, because he was still weak.

Commentary on Matthew ↗

Remigius of Rheims

We ought to admire and at the same time to imitate the humility and mercifulness of the Lord; as soon as ever He was asked, He rose to follow him that asked; And Jesus rose, and followed him. Here is instruction both for such as are in command, and such as are in subjection. To these He has left an example of obedience; to those who are set over others He shows how earnest and watchful they should be in teaching; whenever they hear of any being dead in spirit, they should hasten to Him; And his disciples went with him.

Catena Aurea by Aquinas ↗