Augustine of Hippo
Catena Aurea · Matthäusevangelium 9
Then came to him the disciples of John, saying, Why do we and the Pharisees fast oft, but thy disciples fast not? And Jesus said unto them, Can the children of the bridechamber mourn, as long as the bridegroom is with them? but the days will come, when the bridegroom shall be taken from them, and then shall they fast. No man putteth a piece of new cloth unto an old garment, for that which is put in to fill it up taketh from the garment, and the rent is made worse. Neither do men put new wine into old bottles; else the bottles break, and the wine runneth out, and the bottles perish: but they put new wine into new bottles, and both are preserved.
(De Cons. Ev. ii. 27.) That Matthew writes here mourn, where Mark and Luke write fast, shews that the Lord spake of that kind of fasting which pertains to humbling one’s self in chastisement; as in the following comparisons He may be supposed to have spoken of the other kind which pertains to the joy of a mind wrapt in spiritual thoughts, and therefore averted from the food of the body; shewing that those who are occupied about the body, and owing to this retain their former desires, are not fit for this kind of fasting.