Theophylact of Ohrid

Look how briefly and concisely he speaks in the present case, because children are not able to follow a lengthy discourse. And besides, if a husband will conform to the laws which he set forth above, little effort is needed to bring children into submission. But he does not speak of the Kingdom or of anything lofty, but points to what the childish soul especially desires to hear, because his word is addressed to children. And what is more pleasant for children than long life? …

Commentary on Ephesians ↗

Jerome

What is promised in honoring one's father and mother is not intended for the Jews alone, nor was it intended as an outright financial exchange.… For there surely have been many who, even while being obedient to their parents, died abruptly. Others who have been irreverent to their parents have reached extreme old age.… Rightly interpreted, the command looks for the land that the Lord promises to Israel. It is offered to those who have left the spiritual Egypt. …

Commentary on Ephesians 6:1 ↗

Thomas Aquinas

On this account he adds that you may live long upon the earth. In the Old Testament temporal promises were pledged because the people then were immature and hence were graciously taught as children under a tutor. Nevertheless, in those little gifts which were suited to a young people, great spiritual favors were symbolized. Therefore this text can refer, according to its literal meaning, to temporal goods; which is why he says with a promise, that it may be well with you, that is, that you may abound in the promised benefits. …

Commentary on Ephesians ↗

Bonaventure

By reason of governance, the honor of obedience is owed to the father; whence the Apostle to the Ephesians: Children, obey your parents, for this is just. Honor your father and your mother: which is the first commandment with a promise, that it may be well with you, and that you may be long-lived upon the earth.

Collationes de Decem Praeceptis, Collation 5 ↗