The following is from thewestminsterstandard.org:
Q. 41. Where is the moral law summarily comprehended?
A. The moral law is summarily comprehended in the ten commandments.
Q. 42. What is the sum of the ten commandments?
A. The sum of the ten commandments is, to love the Lord our God, with all our heart, with all our soul, with all our strength, and with all our mind; and our neighbor as ourselves.
Q. 43. What is the preface to the ten commandments?
A. The preface to the ten commandments is in these words, I am the Lord thy God, which have brought thee out of the land of Egypt, out of the house of bondage.
Q. 44. What doth the preface to the ten commandments teach us?
A. The preface to the ten commandments teacheth us, that because God is the Lord, and our God, and Redeemer, therefore we are bound to keep all his commandments.
Q. 45. Which is the first commandment?
A. The first commandment is, Thou shalt have no other gods before me.