A.T. Robertson Commentary Luke 10:27

"And he answering said, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy strength, and with all thy mind; and thy neighbor as thyself." — Luke 10:27 (ASV)

And he answering (ο δε αποκριθεις). First aorist participle, no longer passive in idea. The lawyer's answer is first from the Shema (Deuteronomy 6:3; Deuteronomy 11:13) which was written on the phylacteries. The second part is from Le 19:18 and shows that the lawyer knew the law. At a later time Jesus himself in the temple gives a like summary of the law to a lawyer (Matthew 22:34–40) who wanted to catch Jesus by his question. There is no difficulty in the two incidents. God is to be loved with all of man's four powers (heart, soul, strength, mind) here as in Mr 12:30.