A scribe asked Jesus a question, “Teacher, which is the great commandment in the law?” Jesus said to him,
“‘You shall love the Lord your God with all your heart, with all your soul, and with all your mind.’ This is the first and great commandment.
And the second is like it: ‘You shall love your neighbor as yourself.’ On these two commandments hang all the Law and the Prophets.” (Matthew 22:34-40)
When we think of commandments we think of the Ten Commandments (Deuteronomy 5:6-22). Are not the ten commandments of most importance? The scribe had asked what was the most important of the law, a trick question. The scribes were students of the law of the Torah, the Law of Moses, the first five books of the old covenants which we call the old testament today. There are 613 commandments listed in the Torah[1], so the answer Jesus gave baffled them, as it is not one of the ten commandments but one of the 613 laws. This commandment was the most importance to God and it was one law most of them were not obeying, so was the one like it "you shall love your neighbor as yourself: I am the Lord" (Leviticus 19:18).
This law or greatest commandment was spoken by Moses to Israel after giving them the ten commandments,““Hear, O Israel: The Lord our God, the Lord is one! You shall love the Lord your God with all your heart, with all your soul, and with all your strength. 'And these words which I command you today shall be in your heart'" (Deuteronomy 6:4-5). These scribes and Pharisees knew the law, all 613 of them, but it is evident the laws were not in their heart. They did not obey; "to love the Lord your God, to walk in all His ways and hold fast to Him" (Deuteronomy 11:22).
In the story of David we see the lesson of the greatest commandment. Why did God chose him over Saul? What did Saul do that was so wrong? He seemed to be doing "good things", making a sacrifice and not killing all the people or livestock. Saul disobeyed God but he did not break any of the ten commandments. David broke two of the ten commandments, adultery and murder. Doesn't this seem like a contradiction? Not if there is a greatest commandment. Saul disobeyed God because he feared the people more than loving God (1 Samuel 15: 4), he broke the greatest commandment. David broke other commandments but obeyed the greatest commandment. God said David was "a man after my heart, who will do all I wish" (Acts 13:22). God chose David over Saul.
This is a lesson that is repeated throughout the bible; “God sees not as man sees, for man looks at the outward appearance, but the LORD looks at the heart” (1 Samuel 16:7). Man judges by the external, God judges the heart. This is the lesson Jesus is repeating and saying; your heart is of most important to God, God loves you and wants you to love Him, which is the greatest commandment. God help us, 2000 years later and we still don't get this greatest commandment and the one like it.
“The Lord God, compassionate and gracious, slow to anger, and abounding in loving kindness and truth;" (Exodus 34:6).
[1] Wikipedia. "613 Commandments." http://en.wikipedia.org/wiki/613_commandments (accessed Jan 28, 2013)