קבלה אויף שמות 5:1

Therefore, when Moshe went to Pharaoh as HaShem’s-יהו״ה emissary, blessed is He, he began with the word “Thus-Koh-כה,” since it is the opening by which to enter the Name HaShem-יהו״ה, blessed is He. This is as written,²²⁴Exodus 5:1 “Afterwards, Moshe and Aharon came and said to Pharaoh, ‘Thus-Koh-כה said HaShem-יהו״ה, the God of Israel, ‘Send out My people etc.’” The next verse continues,²²⁵Exodus 5:2 “Pharaoh replied: ‘Who is HaShem-יהו״ה that I should heed His voice to send Israel out? I do not know HaShem-יהו״ה.” Moshe therefore responded, “If you do not know HaShem-יהו״ה, then what you must know is that the first gateway through which one enters the knowledge of Him, is His Divine quality called, ‘Thus-Koh-כה.’”