Why do we say, in a singular term, Zeh Eli, this is my God? That’s Lashon Yachid, singular term. It should have said, Zeh Eloheinu ve'anvehu, this is our God, the plural word, and a plural word, and I'll beautify Him. It should have said, Zeh Eloheinu, Zeh Eloheinu, this is our God. It doesn't say that. It says that He said, Zeh Eli, this is my God, in a singular term, ve'anvehu, and I will beautify Him. Why in a singular term?
So the commentaries say: for a person to do ve'anvehu, for a person to actually enjoy Judaism, beautify his mitzvot (commandments), and appreciate it, and value it, he has to know the first part of the verse: Zeh Eli, Hashem is yours, and you're Hashem's. Every person has their own personal diary with HaKadosh Baruch Hu, with God. Every individual, God wants him or her to serve Him. Don't serve Hashem only because of your parents, your neighbors, or your rabbis. Serve Hashem because Hashem wants you to serve Him. He wants you specifically to serve Him. That's what it says, Zeh Eli.