According to Hashem's instructions, when should the Torah have been given?
Rashi and Targum Yonasan: Hashem instructed Moshe on the fourth of Sivan to prepare themselves for two days (the fourt and the fifth of Sivan) and that on the third day (the sixth of Sivan) Hashem would reveal Himself to the people and give the Torah.
What What is the significance of the preparation?
Rashi: Since they were now destined to hear the Aseres ha'Dibros directly from Hashem, they would require a process of purification 1 that would last for three days - from the fourth to the sixth of Sivan, 2 as the Pasuk goes on to explain.
What is the meaning of "Vekidashtem"?
Rashi, Ramban #1 (citing Onkelos) and Seforno: It means "Prepare yourselves". 1
Ramban #2 (citing Ibn Ezra): It means 'Tovel in water'. 2
Ramban #3: It means "Sanctify yourselves" - by keeping away from your wives and from all kinds of Tum'ah. 3
See Ramban's objection to this explanation.
What did the preparation entail?
Rashi and Seforno: It entailed separating from their wives (abstaining from intimacy). 1
Why did they need to wash their clothes?
Mechilta and Yevamos, 46b: Whenever the Pasuk mentions Kibus Begadim, it means that there was Tevilah as well. 1
Where was this Pasuk said to Moshe? When was it said?