פּירוש אויף שמות 19:3

ומשה עלה AND MOSES WENT UP on the second day of the month (Mekhilta); for all his ascents to the mountain were made early in the morning, as it is stated (Exodus 34:4) “And Moses rose up early in the morning [and went up unto mount Sinai]” (Shabbat 86b).

ומשה עלה, “and Moses had ascended;” he ascended the Mountain on the second day of the month, i.e. on a Tuesday. He had not done so spontaneously but in response to an invitation by G-d, Who had called to him from the Mountain to address the whole nation, i.e. כה תאמר לבית יעקב וגו', “thus you shall say to the house of Yaakov, etc.”Some commentators believe that Moses did ascend the Mountain without having asked for permission in order to enquire how precisely to serve G-d there. He did so as G-d had told him in Exodus 3,12 in response to his enquiry why the Jews were going to be redeemed long before the 400 years of which G-d had spoken to Avraham in Genesis chapter 15 had been concluded. At that time G-d had told him that the people would accept the Torah at this mountain, and that in anticipation of that they were being redeemed ahead of time, “on credit,” so to speak. Actually, we find that the Israelites offered sacrifices near the Mountain prior to the revelation as reported in chapter 24,4-6.

AND MOSES WENT UP UNTO G-D. From the day they arrived at Mount Sinai, the cloud covered the mountain and the Glory of G-d was there. It is with reference to this that Scripture says, And the Glory of the Eternal abode upon Mount Sinai, and the cloud covered it six days,¹⁴⁹Further, 24:16. i.e., before the Giving of the Torah. It is for this reason that Scripture says here, And Moses went up unto G-d, meaning that he went up to the edge of the mountain to be ready for Him, but he did not penetrate the thick darkness where G-d was.¹⁵⁰Ibid., 20:18. And the Eternal called unto him from the top of the mountain, saying: Thus shalt thou say to the house of Jacob.
And Rabbi Abraham ibn Ezra wrote that the expression, and He called unto him, is an antecedent, meaning that He had called him [to come up to the mountain] and he went up to Him. But this does not appear to me to be correct, for the calling [mentioned in Scripture after Moses ascended the mountain] was: Thus shalt thou say to the house of Jacob. Now Ibn Ezra explains the verse to mean as follows: “And the Eternal called unto him to say¹⁵¹Thus Ibn Ezra here interprets the word leimor, which is generally taken to mean “saying,” as meaning “to say.” The sense of the verse is thus: And Moses went up to G-d, for He had called him out of the mountain to tell him, “Thus shalt thou say to the house of Jacob, etc.” to him, Thus shalt thou say to the house of Jacob.” But this is not correct.
The meaning of the expression, he went up unto G-d, and the Eternal called unto him, is that Moses went up towards the Glory of G-d, which was abiding on the mountain to declare the Ten Commandments to Israel, and with His Great Name [the Tetragrammaton] He would speak with Moses, as is the meaning of the verse, If there be a prophet among you, etc.¹⁵²Numbers 12:6. If there be a prophet among you, I the Eternal do make Myself known unto him in a vision… My servant Moses is not so… with him do I speak mouth to mouth, even manifestly, and not in dark speeches (Verses 6-8). See also Ramban in this chapter, further, Verse 20.

כה תאמר THUS SHALT THOU SAY — Thus, i. e. in this (the Hebrew) language (cf. Mekhilta) and in this form of words.