1)
What is the significance of the word "Leyasreka" ('to chastise you') mentioned in connection with Hashem's Voice that they heard on Har Sinai and the fire that they saw there?
1.
Seforno: It teacdhes us that Hashem frightened them when He showed them these things, in order to raise them to the level of prophets. 1
1
Refer to 4:32:2:2. Seforno - Indeed, we find the same two revelations were shown to Eliyahu as he was about to prophesy - See Melachim 1, 19:11 & 12.
2)
How will we reconcile the fact that Hashem's Voice was heard from the Heaven whilst His Fire and words appeared on Har Sinai?
1.
Refer to Sh'mos, 20:19:3:1, 2 & 3.
