Theophylact of Ohrid

He gives the loaves to the disciples so that they might always retain the miracle in their memory and not have it fade from their minds, although they did in fact immediately forget. There was food left over lest you think that He performed the miracle only in appearance. There were twelve baskets so that Judas too might carry one and thus remembering the miracle not rush headlong into betrayal. …

Commentary on Matthew ↗

Jerome

And when he had commanded the multitude to recline upon the hay. The sense is clearly evident according to the letter: let us reveal the sacraments of spiritual interpretation. They are commanded to recline upon the hay, and according to another Evangelist (Luke 9), upon the ground, by fifties or hundreds, so that after they have trampled upon their flesh and all its desires, and subjected all the pleasures of this world to themselves like dry hay, then by the number fifty they may ascend through penitence to the summit …

Commentary on Matthew ↗

Hilary of Poitiers

But the Lord answered, They have no need to go, shewing that those whom He heals have no need of the food of mercenary doctrine, and have no necessity to return to Judaea to buy food; and He commands the Apostles that they give them food. Did He not know then that there was nothing to give them? …

Catena Aurea by Aquinas ↗

Thomas Aquinas

And when he had commanded the crowd to recline upon the grass etc. Here the arrangement of the people is presented, because he made them sit upon the grass; Isa. 40:6: all flesh is grass. To sit upon the grass, therefore, is nothing other than to mortify the flesh. Col. 3:5: mortify your members which are upon the earth. Likewise, the grass signifies the law. Because these were Jews, they were supported by the law; therefore he did not wish them to sit on the ground. Having taken the five loaves and the two fishes etc. …

Commentary on Matthew ↗