Another interpretation: “God spoke to Moses” – Rabbi Meir said: This is analogous to a flesh and blood king who was marrying off his daughter. He summoned a villager to serve as an intermediary between them [the king and his prospective son-in-law’s family]. He [the villager] began speaking presumptuously with him [the king]. The king said: ‘Who caused you to be so arrogant?
Surely it was me, who appointed you intermediary.’ Likewise, the Holy One blessed be He said to Moses: ‘Who caused you to speak these words? It was I, who elevated you.’ Rabbi Yehuda said: So said Moses: ‘When You said to me: “Go now, and I will send you to Pharaoh” (Exodus 3:10), You said to me that you are destined to deliver them with the attribute of mercy.
Perhaps by the time I came it was transformed into the attribute of justice.’ The Holy One blessed be He said to him: “I am the Lord.” I remain in the attribute of mercy; that is: “And said to him: I am the Lord.”