Exodus 6:2

וידבר אלהים אל משה AND GOD SPOKE UNTO MOSES — He took him to task because he had spoken so censoriously when he said, (Exodus 5:22) “Wherefore hast thou done so evil to this people”. ויאמר אליו אני ה׳ AND HE SAID UNTO HIM, I AM THE LORD, Who am faithful to recompense with a full reward those who walk before Me. Nor have I sent you with no purpose in view (cf. 5:22), but to fulfil the promise which I made to the early patriarchs. In this sense we find that the phrase is to be explained in many passages: אני ה׳ signifies, I am the Lord, Who am faithful to exact punishment — when it is spoken in reference to a matter that demands punishment, as, for instance, (Leviticus 19:12) “And thou profanest the name of thy God; I am the Lord”; and when it is spoken in reference to observing the Divine commands — as in, (Leviticus 22:31) “Ye shall keep my commandments and do them; I am the Lord” — it signifies, “I am the Lord Who am faithful to give reward.”

וַיְדַבֵּ֥ר אֱלֹהִ֖ים אֶל־מֹשֶׁ֑ה וַיֹּ֥אמֶר אֵלָ֖יו אֲנִ֥י יְהֹוָֽה׃

And God spoke to Moshe, and said to him, I am the Lord: