Shemot 19:11

11 And be ready by Yom HaShelishi; for Yom HaShelishi Hashem will come down in the sight of kol HaAm upon Mt. Sinai.

Shemot 19:11 Meaning and Commentary

Exodus 19:11

And be ready against the third day
Not the third day of the month, but the third day from hence, this being the fourth, and the morrow the fifth, and the third day, the day following that, the sixth, on which day it is generally agreed by the Jews that the law was given, (See Gill on Exodus 19:16)

for the third day the Lord will come down in the sight of all the
people upon Mount Sinai;
which must be understood, consistent with his omnipresence, and is only expressive of some visible display of his power, and of some sensible token of his presence to the people; he was now upon it in the pillar of cloud, but then he would appear in another manner, and descend in a thick cloud and fire, which all the people would see, though they could not see the similitude of anything in it.

Shemot 19:11 In-Context

9 And Hashem said unto Moshe, Hinei, I am coming unto thee in a thick cloud, that HaAm may hear when I speak with thee, and believe thee l’olam. Then Moshe told the words of HaAm unto Hashem.

10 So Hashem said unto Moshe, Go unto HaAm, and set them apart as kodesh today and tomorrow, and let them wash their clothing,

11 And be ready by Yom HaShelishi; for Yom HaShelishi Hashem will come down in the sight of kol HaAm upon Mt. Sinai.

12 And thou shalt set boundaries unto HaAm all around, saying, Take heed to yourselves, that ye go not up into HaHar, or touch the edge of it; whosoever toucheth HaHar shall be surely put to death;

13 There shall no yad touch him, but he shall surely be stoned, or surely mortally shot; whether it be behemah or ish, it shall not live; when the yovel soundeth long, they shall come up to HaHar.