Or HaChaim on Deuteronomy 5:5/אור החיים על דברים ה׳:ה׳

1 אנכי עומד בין ה׳ וביניכם, "I was standing between the Lord and between you, etc." This verse means that for part of the Ten Commandments G'd spoke with the people face to face, whereas during part of the Ten Commandments He spoke to them through an intermediary. The reason G'd employed an intermediary for part of the Ten Commandments was not His unwillingness to speak to the people directly, but to their fear of dying.

2ולא עליתם בהר לאמור. "and you did not ascend the mountain, saying." This means that G'd forbade you to ascend the mountain because of His wanting to say: אנכי ה׳ אלוקיכם, "I am the Lord your G'd, etc."