Matthew
Matthew 22:39ESV·traditional attribution

And a second is like it: You shall love your neighbor as yourself.

John Calvin Reformed @genevareformer

39. And the second is like it. He assigns the second place to mutual kindness among men, for the worship of God is first in order. The commandment to love our neighbors, he tells us, is like the first, because it depends upon it.

John Gill Reformed Baptist @doctorgill

Saying, what think ye of Christ,.... Or the Messiah; he does not ask them whether there was, or would be such a person in the world. He knew, that he was so plainly spoken of in the writings of the Old Testament, which they had in their hands, that they could not be ignorant, that such a person was prophesied of: he knew that they...

Albert Barnes Presbyterian @notesbybarnes

Verse 39. The second is like unto it. . Resembles it in importance, dignity, purity, and usefulness. This had not been asked by the lawyer, but Jesus took occasion to acquaint him with the substance of the whole law. For its meaning, . Comp. . Mark adds, There is no greater commandment than these. None respecting circumcision or sacrifice is greater. They are the fountain of all.