There is no need for an honest man of integrity to swear by anything. A yes or no should be reliable enough. Men without reliability or trustworthiness swear by oaths, as some sort of superstition that takes the Lord’s name in vain, rather than reverence- too easily is the name of God thrown into bargains and politics. Yet, nothing men swear by belongs to them. All is God’s.
The law was not meant to justify revenge or retaliation, for which the people used it. It was meant to say that the punishment must fit the crime. Endure an insult to keep the peace Christ requires. It is better to walk away from a fight than to engage in one and find yourself hurt or carrying the burden sin of assault or murder. Needless killing is abundant in this world, and cycles throughout history, among those who need only need to heed the words of Jesus and walk away. How can we be peacemakers if we retaliate at every insult? Jesus does not take away the right to self-defense, it is vengeance he criticized. Do everything you can to keep peace, and witness peace to others. By law, a man was allowed to keep his cloak- this was a provision for the poor, who used the cloak as a blanket by night. But Jesus says to give that also, and that if you are forced to walk one mile, walk two. These are not measures of weakness, nor do they come at the cost of self-respect. They are statements of strength, and faith. It is a greater strength- it is overcoming evil by doing good. It is better to lose our money or property than our souls by engaging in evil. Do not repay evil with evil.
Give to one who asks of you, regardless of who it is. We received mercy from God. Are not the poor and needy asking for mercy when they ask for food or clothes? Give and lend with wisdom, not foolishly, or in a way that enables poor behavior or actions against the teachings of Jesus. But do not hold back, that which is good, and you have freely to give.
Love your enemy. Only love can turn your enemy to a friend. It was previously taught only to to love your neighbor. How easy it is to love our friends! What spiritual reward is their in loving our friends, as even those who are corrupt can do that. Jesus asked for a much higher love- the same love that God gives to us as his children. The sun rises on the evil and the good, the rain falls on the righteous and the unrighteous- there is no distinction, God loves everyone. We have all sinned, we are all in need of grace. As God is perfect, we must be perfect. We cannot help but recognize the impossibility! We are sinners, imperfect by nature. Yet Christ called us to be perfect, not so we would be distressed, but so we may lean on him, to attain our perfection. Through Jesus we are made holy.