שמות יט:ט פירוש: רש״י, רמב״ן, ספורנו ואור החיים

בעב הענן signifies in the thickness of the cloud, and this is the ערפל, the thick darkness mentioned in Exodus 20:18 “And Moses stepped near unto the thick darkness where God was” (Mekhilta d'Rabbi Yishmael 19:9:1).

IN A THICK CLOUD. This is the thick darkness where G-d was,¹⁸⁷Further, 20:18. and all the people saw it and recognized it as such, as it is said, And the appearance of the Glory of the Eternal was like devouring fire on the top of the mount in the eyes of the children of Israel.¹⁸⁸Ibid., 24:17.

בעב הענן, even though all of Moses’ prophetic stature underwent a drastic change on the occasion of the revelation at Mount Sinai, and he now received “clear” messages, something described in Numbers 12,8 as ותמונת ה' יביט, “he sees the message from G’d as a clear picture” (not merely as a reflection by a mirror) he was not to behold the Shechinah, but it was shrouded in thick cloud. The present communication with G’d which Moses used was not of the אספקלריא מאירה, “clear view” type.