Sforno on Exodus 19:11/ספורנו על שמות י״ט:י״א

1והיו נכונים, that not only the mind, the spirit, be in readiness for the revelation but also the body that houses the spirit. This was necessary because the level of prophecy they would experience at the revelation would far surpass anything an ordinary prophet experiences, something for which he does not have to prepare his body by ritual immersion, and loss of any residue of seminal fluids the body ejaculated during the days immediately preceding the prophetic vision. Moses was not forbidden physical contact with his own wife until he had attained this level of prophetic stature. This would commence from the time of the revelation and onwards. At that time he released the other Israelites from the restriction of carrying on marital relations with their wives by saying to them: “return to your tents” (Deuteronomy 5,27-28). Moses himself had been told by G’d at that time: “you remain standing here with Me.” This is what our sages explained in Shabbat 87.