The number ten is traditional, but different groups count the commandments differently. In some traditions it is as follows. Others remove "Thou shalt make no graven images" from the first commandment, call it the second commandment, then renumber the following commandments, and combine what we call the ninth and tenth into the tenth. The substance of the Ten is the same.
The Commandments are God's Law. The first three Commandments tell us how we are to love God. The remaining seven Commandments tell us how we are to love our fellow man.
What does Martin Luther says about God's Commandments?
How we are to love God...
I am the Lord Thy God.
Thou shalt have no other gods before me.
Thou shalt make no graven images.
Luther: We are to fear, love, and trust God above anything else.
Thou shalt not take the Name of the Lord thy God in vain.
Luther: We should fear and love God, and so we should not use His Name to curse, swear, practice witchcraft, lie, or deceive; but in every time of need call upon Him, pray to Him, and give Him thanks.
Remember the Sabbath Day to keep it holy.
Luther: We should fear and love God, and so should not neglect His Word or the preaching of it, but regard it as holy, and gladly hear and learn it.
How we are to love our neighbors as ourselves...
Thou shalt honor they father and thy mother,
that it may be well with thee,
and thou mayest live long on the earth.
Luther: We should fear and love God, so that we do not despise or anger our parents and those in authority, but respect, obey, love, and serve them.
Thou shalt not kill.
Luther: We should fear and love God, and so we shuld not endanger our neighbor's life, nor cause him any harm, but help and befriend him in every necessity of life.
Thou shalt not commit adultery.
Luther: We should fear and love God, and so we should lead a chaste and pure life in word and ded, each one loving and honoring his wife or her husband.
Thou shalt not steal.
Luther: We should fear and love God, and so we should not rob our neighbor of is money or property, nor bring them into our possession by dishonest trade or by dealing shoddy wares, but help him to improve and protect his income and property.
Thou shalt not bear false witness against thy neighbor.
Luther: We should fear and love God, and so that we do not betray, slander, or lie about our neighbor, but defend him, speak well of him, and explain his actions in kindest ways.
Thou shalt not covet they neighbor's house.
Luther: We should fear and love God, and so we should not seek by craftiness to gain possession of our neighbor's inheritance or home, nor to obtain them under pretext of legal right, but be of service and help to him so that he may keep what is his.
Thou shalt not covet they neighbor's wife,
nor his manservant, nor his maidservant,
or his cattle or anything that is they neighbors.
Luther: We should fear and love God, and so we should not abduct, estrange, or entice away our neighbor's wife, servants, or cattle, but encourage them to remain and discharge their duty to him.