Westminster What rules are to be observed for the right understanding of the ten commandments?

A99: For the right understanding of the ten commandments, these [eight] rules are to be observed:

That the law is perfect, and bindeth everyone to full conformity in the whole man unto the righteousness thereof, and unto entire obedience forever; so as to require the utmost perfection of every duty, and to forbid the least degree of every sin.[422]
1. (Psa 19:7) The law of the LORD is perfect, restoring the soul; The testimony of the LORD is sure, making wise the simple.
  
  (Jas 2:10) For whoever keeps the whole law and yet stumbles in one point, he has become guilty of all.
  
  (Mat 5:21-22) "You have heard that the ancients were told, 'YOU SHALL NOT COMMIT MURDER' and 'Whoever commits murder shall be liable to the court.' "But I say to you that everyone who is angry with his brother shall be guilty before the court; and whoever says to his brother, 'You good-for-nothing,' shall be guilty before the supreme court; and whoever says, 'You fool,' shall be guilty enough to go into the fiery hell.
That it is spiritual, and so reaches the understanding, will, affections, and all other powers of the soul; as well as words, works, and gestures.[423]
1. (Rom 7:14) For we know that the Law is spiritual, but I am of flesh, sold into bondage to sin.
  
  (Deu 6:5) "You shall love the LORD your God with all your heart and with all your soul and with all your might.
  
  (Mat 5:21-22, 27-28, 33-34, 37-39, 43-44) "You have heard that the ancients were told, 'YOU SHALL NOT COMMIT MURDER' and 'Whoever commits murder shall be liable to the court.' "But I say to you that everyone who is angry with his brother shall be guilty before the court; and whoever says to his brother, 'You good-for-nothing,' shall be guilty before the supreme court; and whoever says, 'You fool,' shall be guilty enough to go into the fiery hell. . . "You have heard that it was said, 'YOU SHALL NOT COMMIT ADULTERY'; but I say to you that everyone who looks at a woman with lust for her has already committed adultery with her in his heart. . . "Again, you have heard that the ancients were told, 'YOU SHALL NOT MAKE FALSE VOWS, BUT SHALL FULFILL YOUR VOWS TO THE LORD.' "But I say to you, make no oath at all, either by heaven, for it is the throne of God, . . . "But let your statement be, 'Yes, yes' or 'No, no'; anything beyond these is of evil. "You have heard that it was said, 'AN EYE FOR AN EYE, AND A TOOTH FOR A TOOTH.' "But I say to you, do not resist an evil person; but whoever slaps you on your right cheek, turn the other to him also. . . "You have heard that it was said, 'YOU SHALL LOVE YOUR NEIGHBOR and hate your enemy.' "But I say to you, love your enemies and pray for those who persecute you,"
  
  (Mat 22:37-39) And He said to him, " 'YOU SHALL LOVE THE LORD YOUR GOD WITH ALL YOUR HEART, AND WITH ALL YOUR SOUL, AND WITH ALL YOUR MIND.' "This is the great and foremost commandment. "The second is like it, 'YOU SHALL LOVE YOUR NEIGHBOR AS YOURSELF.'
That one and the same thing, in divers respects, is required or forbidden in several commandments.[424]
1. (Col 3:5) Therefore consider the members of your earthly body as dead to immorality, impurity, passion, evil desire, and greed, which amounts to idolatry.
  
  (Amo 8:5) saying, "When will the new moon be over, So that we may sell grain, And the sabbath, that we may open the wheat market, To make the bushel smaller and the shekel bigger, And to cheat with dishonest scales,
  
  (Pro 1:19) So are the ways of everyone who gains by violence; It takes away the life of its possessors.
  
  (1Ti 6:10) For the love of money is a root of all sorts of evil, and some by longing for it have wandered away from the faith and pierced themselves with many griefs.
That as, where a duty is commanded, the contrary sin is forbidden;[425] and, where a sin is forbidden, the contrary duty is commanded:[426] so, where a promise is annexed, the contrary threatening is included;[427] and, where a threatening is annexed, the contrary promise is included.[428]
1. (Isa 58:13) "If because of the sabbath, you turn your foot From doing your own pleasure on My holy day, And call the sabbath a delight, the holy day of the LORD honorable, And honor it, desisting from your own ways, From seeking your own pleasure And speaking your own word,
  
  (Deu 6:13) "You shall fear only the LORD your God; and you shall worship Him and swear by His name.
  
  (Mat 4:9-10) and he said to Him, "All these things I will give You, if You fall down and worship me." Then Jesus *said to him, "Go, Satan! For it is written, 'YOU SHALL WORSHIP THE LORD YOUR GOD, AND SERVE HIM ONLY.'"
  
  (Mat 15:4-6) "For God said, 'HONOR YOUR FATHER AND MOTHER,' and, 'HE WHO SPEAKS EVIL OF FATHER OR MOTHER IS TO BE PUT TO DEATH.' "But you say, 'Whoever says to his father or mother, "Whatever I have that would help you has been given to God," he is not to honor his father or his mother.' And by this you invalidated the word of God for the sake of your tradition.
2. (Mat 5:21-25) "You have heard that the ancients were told, 'YOU SHALL NOT COMMIT MURDER' and 'Whoever commits murder shall be liable to the court.' "But I say to you that everyone who is angry with his brother shall be guilty before the court; and whoever says to his brother, 'You good-for-nothing,' shall be guilty before the supreme court; and whoever says, 'You fool,' shall be guilty enough to go into the fiery hell. "Therefore if you are presenting your offering at the altar, and there remember that your brother has something against you, leave your offering there before the altar and go; first be reconciled to your brother, and then come and present your offering. "Make friends quickly with your opponent at law while you are with him on the way, so that your opponent may not hand you over to the judge, and the judge to the officer, and you be thrown into prison.
  
  (Eph 4:28) He who steals must steal no longer; but rather he must labor, performing with his own hands what is good, so that he will have something to share with one who has need.
3. (Exo 20:12) "Honor your father and your mother, that your days may be prolonged in the land which the LORD your God gives you.
  
  (Pro 30:17) The eye that mocks a father And scorns a mother, The ravens of the valley will pick it out, And the young eagles will eat it.
4. (Jer 18:7-8) "At one moment I might speak concerning a nation or concerning a kingdom to uproot, to pull down, or to destroy it; if that nation against which I have spoken turns from its evil, I will relent concerning the calamity I planned to bring on it.
  
  (Exo 20:7) "You shall not take the name of the LORD your God in vain, for the LORD will not leave him unpunished who takes His name in vain.
  
  (Psa 15:1, 4-5) . . . O LORD, who may abide in Your tent? Who may dwell on Your holy hill? . . . In whose eyes a reprobate is despised, But who honors those who fear the LORD; He swears to his own hurt and does not change; He does not put out his money at interest, Nor does he take a bribe against the innocent. He who does these things will never be shaken.
  
  (Psa 24:4-5) He who has clean hands and a pure heart, Who has not lifted up his soul to falsehood And has not sworn deceitfully. He shall receive a blessing from the LORD And righteousness from the God of his salvation.
That what God forbids, is at no time to be done;[429] what he commands, is always our duty;[430] and yet every particular duty is not to be done at all times.[431]
1. (Job 13:7-8) "Will you speak what is unjust for God, And speak what is deceitful for Him? "Will you show partiality for Him? Will you contend for God?
  
  (Rom 3:8) And why not say (as we are slanderously reported and as some claim that we say), "Let us do evil that good may come"? Their condemnation is just.
  
  (Job 36:21) "Be careful, do not turn to evil, For you have preferred this to affliction.
  
  (Heb 11:25) choosing rather to endure ill-treatment with the people of God than to enjoy the passing pleasures of sin,
2. (Deu 4:8-9) "Or what great nation is there that has statutes and judgments as righteous as this whole law which I am setting before you today? "Only give heed to yourself and keep your soul diligently, so that you do not forget the things which your eyes have seen and they do not depart from your heart all the days of your life; but make them known to your sons and your grandsons.
3. (Mat 12:7) "But if you had known what this means, 'I DESIRE COMPASSION, AND NOT A SACRIFICE,' you would not have condemned the innocent.
That under one sin or duty, all of the same kind are forbidden or commanded; together with all the causes, means, occasions, and appearances thereof, and provocations thereunto.[432]
1. (Mat 5:21-22, 27-28) "You have heard that the ancients were told, 'YOU SHALL NOT COMMIT MURDER' and 'Whoever commits murder shall be liable to the court.' "But I say to you that everyone who is angry with his brother shall be guilty before the court; and whoever says to his brother, 'You good-for-nothing,' shall be guilty before the supreme court; and whoever says, 'You fool,' shall be guilty enough to go into the fiery hell. . . . "You have heard that it was said, 'YOU SHALL NOT COMMIT ADULTERY'; but I say to you that everyone who looks at a woman with lust for her has already committed adultery with her in his heart.
  
  (Mat 15:4-6) "For God said, 'HONOR YOUR FATHER AND MOTHER,' and, 'HE WHO SPEAKS EVIL OF FATHER OR MOTHER IS TO BE PUT TO DEATH.' "But you say, 'Whoever says to his father or mother, "Whatever I have that would help you has been given to God," he is not to honor his father or his mother.' And by this you invalidated the word of God for the sake of your tradition.
  
  (Heb 10:24-25) and let us consider how to stimulate one another to love and good deeds, not forsaking our own assembling together, as is the habit of some, but encouraging one another; and all the more as you see the day drawing near.
  
  (1Th 5:22) abstain from every form of evil.
  
  (Jud 1:23) save others, snatching them out of the fire; and on some have mercy with fear, hating even the garment polluted by the flesh.
  
  (Gal 5:26) Let us not become boastful, challenging one another, envying one another.
  
  (Col 3:21) Fathers, do not exasperate your children, so that they will not lose heart.
That what is forbidden or commanded to ourselves, we are bound, according to our places to endeavour that it may be avoided or performed by others, according to the duty of their places.[433]
1. (Exo 20:10) but the seventh day is a sabbath of the LORD your God; in it you shall not do any work, you or your son or your daughter, your male or your female servant or your cattle or your sojourner who stays with you.
  
  (Lev 19:17) 'You shall not hate your fellow countryman in your heart; you may surely reprove your neighbor, but shall not incur sin because of him.
  
  (Gen 18:19) "For I have chosen him, so that he may command his children and his household after him to keep the way of the LORD by doing righteousness and justice, so that the LORD may bring upon Abraham what He has spoken about him."
  
  (Jos 14:15) Now the name of Hebron was formerly Kiriath-arba; for Arba was the greatest man among the Anakim. Then the land had rest from war.
  
  (Deu 6:6-7) "These words, which I am commanding you today, shall be on your heart. "You shall teach them diligently to your sons and shall talk of them when you sit in your house and when you walk by the way and when you lie down and when you rise up.
That in what is commanded to others, we are bound, according to our places and callings, to be helpful to them;[434] and to take heed of partaking with others in what is forbidden them.[435]
1. (2Co 1:24) Not that we lord it over your faith, but are workers with you for your joy; for in your faith you are standing firm.
2. (1Ti 5:22) Do not lay hands upon anyone too hastily and thereby share responsibility for the sins of others; keep yourself free from sin.