John Chrysostom

For because death to the Jews, who did all things for the present life, seemed an unmixed evil, Moses ordered that the wife of one who died without sons should be given to his brother, that a son might be born to the dead man by his brother, and his name should not perish, which was some alleviation of death. …

Catena Aurea by Aquinas ↗

Jerome

And they asked him, saying: Master, Moses said: If any man die, having a wife, and he have no children, that his brother should take her to wife, and raise up seed to his brother. Now there were with us seven brethren: and the first, having taken a wife, died; and, not having issue, left his wife to his brother. In like manner the second and the third, unto the seventh. And last of all the woman died also. …

Commentary on Matthew ↗

Thomas Aquinas

There follows the question. And first he presents the law; secondly, the case; thirdly, the question. They say, therefore, and they interrogated him, saying: master, Moses said: if a man die, having no son, etc. Deuteronomy 25:5 f. What was the reason for the law? The people were carnal. Hence they sought nothing but temporal things. The law, therefore, promised these. …

Commentary on Matthew ↗