Matthew Henry on the Death Penalty for Cursing One's Parents

On Jesus' upholding of the capital sanction for cursing one's parents in Matthew 15:4, which reads, "For God commanded, saying, Honour thy father and mother: and, He that curseth father or mother, let him die the death" (see verses below this quotation for broader context), Reformed commentator Matthew Henry writes:

Matthew Henry

"[1.] Let us see what the command of God is (v. 4), what the precept, and what the sanction of the law is.

The precept is, Honour thy father and thy mother; this is enjoined by the common Father of mankind, and by paying respect to them whom Providence has made the instruments of our being, we give honour to him who is the Author of it, who has thereby, as to us, put some of his image upon them. The whole of children's duty to their parents is included in this of honouring them, which is the spring and foundation of all the rest, If I be a father, where is my honour? Our Saviour here supposes it to mean the duty of children's maintaining their parents, and ministering to their wants, if there be occasion, and being every way serviceable to their comfort. Honour widows, that is, maintain them, 1 Tim. v. 3.

"The sanction of this law in the fifth commandment, is, a promise, that thy days may be long; but our Saviour waives that, lest any should thence infer it to be only a thing commendable and profitable, and insists upon the penalty annexed to the breach of this commandment in another scripture, which denotes the duty to be highly and indispensably necessary; He that curseth father or mother, let him die the death: this law we have, Exod. xxi. 17. The sin of cursing parents is here opposed to the duty of honouring them. Those who speak ill of their parents, or wish ill to them, who mock at them, or give them taunting and opprobrious language, break this law. If to call a brother Raca be so penal, what is it to call a father so? By our Saviour's application of this law, it appears, that denying service or relief to parents is included in cursing them. Though the language be respectful enough, and nothing abusive in it, yet what will that avail, if the deeds be not agreeable? it is but like him that said, I go, Sir, and went not, ch. xxi. 30."
Matthew Henry, Commentary on the Whole Bible: Volume Five, Matthew Chapter 15

Matthew 15:1-9 (KJV):

¹Then came to Jesus scribes and Pharisees, which were of Jerusalem, saying,

 ²Why do thy disciples transgress the tradition of the elders? for they wash not their hands when they eat bread.
 ³But he answered and said unto them, Why do ye also transgress the commandment of God by your tradition?
 ⁴For God commanded, saying, Honour thy father and mother: and, He that curseth father or mother, let him die the death.
 ⁵But ye say, Whosoever shall say to his father or his mother, It is a gift, by whatsoever thou mightest be profited by me;
 ⁶And honour not his father or his mother, he shall be free. Thus have ye made the commandment of God of none effect by your tradition.
 ⁷Ye hypocrites, well did Esaias prophesy of you, saying,
 ⁸This people draweth nigh unto me with their mouth, and honoureth me with their lips; but their heart is far from me.
 ⁹But in vain they do worship me, teaching for doctrines the commandments of men.