Albert Barnes Commentary Mark 12:28

"And one of the scribes came, and heard them questioning together, and knowing that he had answered them well, asked him, What commandment is the first of all?" — Mark 12:28 (ASV)

Verse 28. Perceiving that he answered them well. That is, with wisdom, and with a proper understanding of the law. In this case, the opinion of the Saviour corresponded with that of the Pharisees; and this question seems to have been one of the very few candid inquiries asked of him by the Jews for the purpose of obtaining information. Jesus answered it in a similar spirit of kindness and commended the conduct of the man.