What did Moses and God do on that mountain that day? Remember, it was the closest that Moses had ever come to God. It was their most intimate encounter. Maybe it didn't last very long. But during those moments, what did God want to reveal to Moses?
Two things: First, His glory. Second, His Name. The LORD the LORD, the Compassionate and Gracious God, Slow to Anger, Abounding in Love and Faithfulness, Maintaining Love to Thousands and Forgiving Wickedness, Rebellion and Sin.
To truly know someone means to know their name.
God even reassures that Moses that He is pleased with Him because He knows him by name (Ex. 33:17).
God and Moses were friends. They spoke to each other face to face. They beheld each other's form. They experienced hardship together. They knew each other's name.