"Thou shalt have no other gods before Me. Thou shalt not make unto thee any graven image, or any likeness that is of any thing that is in heaven above, or that is in the earth beneath, or that is in the water under the earth. Thou shalt not bow down thyself to them, nor serve them." Spoken by God to Moses on Mount Sinai as recorded in Exodus 20, this is either the Second Commandment (Hebrew and some Protestant reckonings) or the second half of the First Commandment (according to the Catholic way of numbering them).
Little does Moses know at this point that the Israelites, whom he has left behind on the plain while he ascended the mountain to speak with God, are already busily breaking this commandment by making a golden calf to worship. While this commandment seems on the surface to be easily kept, it is one of the most difficult. Most of us are in little danger of bowing down before a statue of a golden calf, but we put other gods before God all the time. Money, power, success, food, drink, politics, our country, our lovers, our careers, our families, ourselves. The world is teeming with false idols masquerading as The Really Important Things. Important they may be, but they are only properly approached through God.