What is the first of the ten commandments or the law of Moses?

Answer 1

They are the ten commands which God spoke at Sinai (Exodus ch.19-20). God inscribed them in the two Stone Tablets and handed the Tablets to Moses (Exodus 31:18); and they were kept in the Ark of the Covenant (Deuteronomy ch.10).

• 1) "Anochi Hashem Elokecha..." (I am the Lord your God....): To believe in God's existence, His concern for the world, His intervention at will in the affairs of the world, and His infinite might.
• 2) "Lo yihyeh lecha ..." (You shall not recognize the gods of others): The prohibition against idolatry.
• 3) "Lo tisa ..." (You shall not use the Name of the Lord your God in vain....): Do not disgrace God's name by using it for no valid purpose. This especially refers to swearing with God's name, an oath that you do not mean to keep or cannot keep.
• 4) "Zachor et yom hashabbat l'kadsho ..." (Remember the day of Shabbat to keep it holy....): Sanctify the day of Shabbat as a day of rest by refraining from work: creative, purposeful interaction with nature. Treat it as a day of delight, by the recitation of Kiddush, the Shabbat meals, etc.
• 5) "Kabed et avicha v'et imecha..." (Honor your father and your mother...): Revering and honoring one's parents is considered a basic commandment in Judaism from the perspective that there are three partners involved in the creation of a human being: one's parents and God Himself. That is why this Commandment is included with the first five, which are considered to be between Man and his Creator. This is also understood, by extension, to refer to teachers.
• 6) "Lo tirtzach" (You shall not murder): Human beings are created in the "image of God." Certain taking of life is sanctioned by the Torah, as is the case in a milchemet mitzvah; an obligatory war. However, outside of the limited exceptions, the diminution of the "Tzelem Elokim," the "image of God" in the world, is one of the three cardinal crimes, for which one must give up his or her life, rather than violate.
• 7) "Lo tin'af" (You shall not commit adultery): the prohibition of cohabiting with a married woman.
• 8) "Lo tignov" (You shall not steal).
• 9) "Lo taaneh ve'reacha ed shahker" (Do not testify falsely against your neighbor): Giving testimony is a very serious matter in Judaism, because it has the power to directly affect someone else's life.
• 10) "Lo tachmod beit rei'echa..." (You shall not covet anything that belongs to your fellow): This is a matter in which the Torah legislates regarding a person's inner thoughts and feelings. Only a Divine Lawgiver could possibly legislate in this way, for He knows the doings within our minds.

See also: More about the Ten Commandments

Answer 2

"Thou shalt have no other gods before me" is the first commandment.