Theophylact of Ohrid

Then, lest anyone say that in the end everything of the Law has been rejected as vain and utterly empty, the Lord says: No! On the contrary, now it is even more fulfilled and accomplished. For what the Law sketched in shadow, speaking figuratively about Christ or about the commandments, is now fulfilled, and not one stroke of it shall be lost. What was indicated there in the form of a shadow concerning Christ is now accomplished in the clearest manner. …

Commentary on Luke ↗

Clement of Alexandria

Perhaps by the iota and tittle His righteousness cries, "If ye come right unto Me, I will also come right to you; but if crooked, I also will come crooked, saith the Lord of hosts;" intimating that the ways of sinners are intricate and crooked. For the way right and agreeable to nature which is intimated by the iota of Jesus, is His goodness, which constantly directs those who believe from hearing, "There shall not, therefore, pass from the law one iota or one tittle," neither from the right and good the mutual promises, nor from the …

From the Catena on Luke, Edited by Corderius ↗

Bede

But lest they should suppose that in His words, the Law and the Prophets were until John, He preached the destruction of the Law or the Prophets, He obviates such a notion, adding, And it is easier for heaven and earth to pass, than one tittle of the law should fail. For it is written, the fashion of this world passeth away. (1 Cor. 7:31.) But of the Law, not even the very extreme point of one letter, that is, not even the least things are destitute of spiritual sacraments. …

Catena Aurea by Aquinas ↗

Bonaventure

Secondly, as regards the fulfillment of the Law according to the spiritual understanding, it is added: But it is easier for heaven and earth to pass away, through the conflagration of the world: Psalm: "And you in the beginning founded the earth. They shall perish," etc. Than for one tittle of the Law to fall, through the frustration of any promise. …

Commentary on Luke, Chapter 16 ↗