In his sermon on The Mount of Blessings, Jesus presented moral law in its real, until then neglected light. Lest He be misunderstood because of emphasizing the spiritual nature of the law as one who abolishes the law, Jesus confirmed that the law was eternal and unchangeable:

"Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfill. For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled. Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven. For I say unto you, That except your righteousness shall exceed the righteousness of the scribes and Pharisees, ye shall in no case enter into the kingdom of heaven." (Matthew 5:17-20)

Pharisees were known by their strict and blind following of God's law and still Jesus said to them:

"Did not Moses give you the law? Yet none of you keeps the law." "You are those who justify yourselves before men, but God knows your hearts; for what is exalted among men is an abomination in the sight of God." (John 7:19; Luke 16:15)

It's not enough that only our feelings, thoughts and behavior are in accordance with the law. The reform has to start from the heart (motives):

"Blessed are the pure in heart: for they shall see God." (Matthew 5:8)

Pharisees presented all commandments of moral Decalogue perverted, because of the formal and superficial understanding of God's justice. Jesus showed the real character of moral law with exact examples of The God's commandments.

About breaking Seventh commandment, Jesus says:

"You have heard that it was said, 'You shall not commit adultery.' But I say to you that every one who looks at a woman lustfully has already committed adultery with her in his heart." (Matthew 5:27-28)

Jesus actually just reminded the Jews of the neglected meaning of the commandments Old Testament:

"... And that you seek not after your own heart and your own eyes, after which you use to go a whoring: That you may remember, and do all my commandments, and be holy unto your God." (Numbers 15:39-40)

Likewise, speaking about love for neighbour and for enemy, Jesus says:

"You have learned that they were told, 'Love your neighbour, hate your enemy'. But I say to you, Love your enemies and pray for those who persecute you, so that you may be sons of your Father who is in heaven; If you love only those who love you, what reward have you? Do not even the tax collectors do the same?" (Matthew 5:43-46)

In the Old Testament was written "Love your neighbour" and the commandment "Hate your enemy" was not written in the Old Testament, because the root was in the church tradition. We know that from Jesus saying: "You have learned that they were told".

Commandment "An eye for an eye, a tooth for a tooth" (Leviticus 24:20) was the Commandment of the civil law (the shadow of God's justice which is going to follow wrongdoing when the last Judgment comes) but the uneducated Jewish people interpreted is as a commandment of moral law because they wanted to justify anger and hate in their hearts. But, the moral law in The Old Testament said:

"You shall not take vengeance." (Leviticus 19:18)

"Do not say, 'I will repay evil'." (Proverbs 20:22)

"Do not say, 'I will do to him as he has done to me; I will pay the man back for what he has done'."

"Do not rejoice when your enemy falls, and let not your heart be glad when he stumbles."

"If your enemy is hungry, give him food to eat; if he is thirsty, give him water to drink." (Proverbs 24:29; 24:17; 25:21)

Jewish wise sayings kept a record for us of the way in which Jews, at the time of the Old Testament, considered the way God treated His enemies, even the enemies who, because of their evil ways, had to be extinct. They say:

"Those who lived long ago in your holy land you hated for their detestable practices, their works of sorcery and unholy rites, their merciless slaughter of children, and their sacrificial feasting on human flesh and blood. These initiates from the midst of a heathen cult, these parents who murder helpless lives, you willed to destroy by the hands of our ancestors, so that the land most precious of all to you might receive a worthy colony of the servants of God. But even these you spared, since they were but mortals, and send wasps as forerunners of your army to destroy them little by little, though you were not unable to give the ungodly in to the hands of the righteous in battle, or to destroy them at one blow by dread wild animals your stern word. But judging them little by little you gave them an opportunity to repent.

For who will say, 'What have you done?' or will resist your judgment? Who will accuse you for the destruction of nations that you made? Or who will cone before you to plead as an advocate for the unrighteous? For neither is there any god besides you, whose care is for all people, to whom you should prove that you have not unjustly; ... You are righteous and you rule all things righteously." (Wisdom of Solomon 12)

God's tenderness is surprising concerning His acting toward the Egyptians. Instead of punishing them with wild beasts His sent lice, grasshoppers and frogs!

"Their land brought forth frogs in abundance, in the chambers of their kings. He spake, and there came divers sorts of flies, and lice in all their coasts. He spake, and the locusts came, and caterpillars, and that without number, And did eat up all the herbs in their land, and devoured the fruit of their ground." (Psalm 105:30-31.34-35)

"If return for their foolish and wicked thoughts, which led them astray to worship irrational serpent and worthless animals, you sent upon them a multitude of irrational creatures to punish them, so that they might learn that one is punished by the very things by which one sins.

For your all-powerful hand, which created the world out of formless matter, did not lack the means to send upon them a multitude of bears, or bold lions, or newly-created unknown beasts full of rage, of such as breathe out fiery breath... But the mere sight of them could kill by fright. ... But you have arranged all things by measure and number and weight. ...

But you are merciful to all, for you can do all things, and you overlook people's sins, so that they may repent. For you love all things that exist, and detest none of the things that you have made, for you would not have made anything if you had hated it. How would anything have endured if you had not willed it? Or how would anything not called forth by you have been preserved? You spare all things, for they are yours. O Lord, you who love the living.

For your immortal spirit is in all things. Therefore you correct little by little those who trespass, and you remind and warn them of the things through which they sin, so that they may be freed from wickedness and put their trust in you, O Lord." (Wisdom of Solomon 11)