Sforno on Exodus 20:15/ספורנו על שמות כ׳:ט״ו

1רואים את, the word רואים as “seeing” is to be understood as like the same word in Kohelet 1,16 ולבי ראה, “and my heart ‘saw.’” Just as the heart cannot see, so people cannot “see” sounds. The meaning is that they understood the meaning of these sounds. They could not continue to endure the volume or nature of thee sounds. The same is explained in greater detail by Moses in Deuteronomy 18,16. They were afraid they would die.

2וירא העם, they understood what they should do.

3וינועו, a word describing involuntary movements of one’s body, trembling. One is unable to arrest one’s motion i.e. that which is known as נע. The word appears transitively in Numbers 32,13 ויניעם במדבר, “He made them wander in the desert.” It occurs intransitively also in Isaiah 24,20 תנוע ארץ כשכור, “the earth is swaying like a drunkard.” The Israelites’ trembling was inspired by the fright they experienced at hearing G’d’s voice.