“Dear friends, I am not writing you a new command but an old command that you have had from the beginning. The old command is the message you have heard.” 1 John 2:7 HCSB

John does not say what his command is, but what He has already said gives us a clue what the old command is. I think the old command is to love God with all your heart, soul, mind, and strength.

“Listen, Israel: The Lord our God, the Lord is One. Love the Lord your God with all your heart, with all your soul, and with all your strength. These words that I am giving you today are to be in your heart.”

Deuteronomy 6:4-6 HCSB

https://www.bible.com/72/deu.6.4-6.hcsb

“Teacher, which command in the law is the greatest? ” He said to him, “Love the Lord your God with all your heart, with all your soul, and with all your mind. This is the greatest and most important command.”

Matthew 22:36-38 HCSB

https://www.bible.com/72/mat.22.36-38.hcsb

“One of the scribes approached. When he heard them debating and saw that Jesus answered them well, he asked Him, “Which command is the most important of all? ” “This is the most important,” Jesus answered: Listen, Israel! The Lord our God, the Lord is One. Love the Lord your God with all your heart, with all your soul, with all your mind, and with all your strength.”

Mark 12:28-30 HCSB

https://www.bible.com/72/mrk.12.28-30.hcsb

“Just then an expert in the law stood up to test Him, saying, “Teacher, what must I do to inherit eternal life? ” “What is written in the law? ” He asked him. “How do you read it? ” He answered: Love the Lord your God with all your heart, with all your soul, with all your strength, and with all your mind; and your neighbor as yourself. “You’ve answered correctly,” He told him. “Do this and you will live.”

Luke 10:25-28 HCSB

https://www.bible.com/72/luk.10.25-28.hcsb

If the Bible repeats it’s self three times we should listen. To love the Lord God with all your heart and soul is repeated all three times. To love the Lord God with all your mind and strength is repeated two times. We discover in verse six that we are to follow Jesus’ example in following God. Which was to love His Father with all His heart, soul, mind, and strength. 

These commands have been around since just after the Ten Commandments. Deuteronomy five contains the recap of the first time God spoke these commands to Moses and all the people of Israel in Exodus 20. And if you sum up the Ten commands 4 would be about loving with all your heart, soul, mind, and strength. The remaining six would be loving other people as you would love yourself. This would predate all the other laws in Moses’ law.

So the old command is to love the Lord God, maker of heaven and earth, with all your heart, soul, mind, and strength and to love your neighbor as yourself.