He had to live perfect, having never had an impure thought; based on what “is written” (as spoken in the previous verse) he eludes to this fact by two scriptures he spake[paraphrased]: ye shall not think to list on a woman or ye have committed adultery in your heart & thou shalt not kill, I say unto you ye shall not be angry with your brother lest ye are in danger of hell fire. His purity for obeying the maximum of the law is expressed by what he taught; and we know that he loved it, for he spake of the hypocrisy constantly.
He had to live perfect, having never had an impure thought; based on what “is written” (as spoken in the previous verse) he eludes to this fact by two scriptures he spake[paraphrased]: ye shall not think to list on a woman or ye have committed adultery in your heart & thou shalt not kill, I say unto you ye shall not be angry with your brother lest ye are in danger of hell fire. His purity for obeying the maximum of the law is expressed by what he taught; and we know that he loved it, for he spake of the hypocrisy constantly.
*correction: list = lust