Having already warned (in the previous Pasuk) against touching the mountain, why does the Torah need to repeat it?
Rashbam: The Torah is referring (not to touching the mountain, but) to touching the sinner by killing him from close quarters, 1 and fulfilling the command by throwing stones or firing arrows at him, as the Pasuk goes on to explain.
Targum Yonasan and Moshav Zekenim: What the Torah is saying is that one may not lay a hand on anyone who comes close to the Mountain, but that he will be stoned (by Hashem) with hailstones or with arrows of fire.
Da'as Zekenim: This Pasuk teaches that he is put to death by stoning - and not by choking - even though Stam Misah (bi'Yedei Adam) is strangulation (Chenek).
Rashbam: Because whoever kills him will then himself be Chayav Misah for committing the same sin.
What did Hashem mean when he added "O Yaroh Yiyareh"?
Rashi: This teaches us that the regular sentence of Sekilah is carried out by pushing the culprit down 1 from the area where the Sekilah takes place.
Rashbam: Refer to 19:13:1:1.
Targum Yonasan: Refer to 19:13:1:2.
Sanhedrin 45a: We learn from "O Yaroh" that the person must be pushed down: from "Ki Sakol" that he must be stoned; From "Sakol Yisakel O Yaroh Yiyareh" that he must be both pushed down and stoned; 2 from "O" that if he died after being pushed, he need not be stoned. And from the double Lashon "Sakol Yisakel" we learn that all this applies to all generations (and not just to Har Sinai).
Yerushalmi Sanhedrin, 6:5: We learn from "O Yar'oh Yiyareh" that he needs to be 'pushed' twice - if he falls on his back, one must turn him on his side. 3
Rashi: From a height of two heights (i.e., six Amos). Also see Rashi to Shemos 15:4, and to Sanhedrin 45a.
Should he not die after being pushed down. See Torah Temimah, note 19.
See Torah Temimah, note 22.
Were wild animals and birds permitted to go on Har Sinai?
What do we learn from the Torah's comparison of Behemah to Ish?
Sanhedrin 15b: It teaches us that, just as a person requires a Beis-Din of twenty-three to declare him Chayav Misah, so too does an animal. 1
See Torah Temimah, note 26.
Why were the animals forbidden to go on the mountain?
Refer to 19:17:1:1 and note 3.
What was the "Yovel"?
Rashi: It was the Shofar that was made from the horn of Yitzchak's ram. 1
Ramban (according to Kabalah): It was the voice of Pachad Yitzchak. 2
Ramban: Which Hashem perhaps re-shaped and formed from the ashes of the ram.
Ramban: See Devarim 4:12 - which explains why the people trembled when they heard it. See Pasuk 16.
What is the meaning of "bi'Meshoch ha'Yovel"?
Rashi #1, Targum Onkelos and Targum Yonasan: It is a long Shofar blast, 1 a sign that the Shechinah 2 had departed.
Rashi #2 (to Beitzah 5b, citing the Mechilta) and Rashbam: It means when the one who is blowing the Shofar withdraws (stops blowing).
Bearing in mind the Pasuk regarding the second Luchos, "Gam ha'Tzon vha'Bakar Al Yir'u El Mul ha'Har ha'Hu" (34:3), implying that the prohibition would be lifted once the Shechinah departed from the mountain, why does the Torah need to add "bi'Meshoch ha'Yovel Heimah Ya'alu ba'Har"?
Beitzah 5b: To teach us that 'A decree that one Beis-Din issues does not become nullified automatically until another Beis-Din nullifies it.' 1
Ta'anis 21b: To teach us that 'It is not the the location that honors the person, but the person who honors the location' - because, as long as the Shechinah was on Har Sinai, it was forbidden to ascend, and the moment it departed ascending it became permitted.
Even though the specified reason no longer applies. See Torah Temimah, note 27 & 28.
QUESTIONS ON RASHI
Rashi writes that "O Yaroh Yiyareh" teaches us that one who is stoned is cast down. But the Torah wrote "Sakol Yisakel" before this, implying that Beis Din cast him down before throwing stones. Within one context, the Torah retains its chronological order (Pesachim 6b)?
Moshav Zekenim #1: The simple meaning 1 of the Pasuk is teaching us that, if someone stands on the mountain - he is killed by throwing stones at him from afar, and if that is not possible, by firing arrows at him. 2
Tosfos (to Pesachim 6b DH 'Aval'), Moshav Zekenim #2 and Riva: The current Derashah is based on the Pasuk, "u'Sekaltam ba'Avanim va'Mesu" (Devarim 17:5), where the Pasuk juxtaposes 'Sekilah' to 'Misah,' implying that stoning occurs after casting down.
Riva, citing R. Meir Kochbi, Hadar Zekenim: The Torah needed to write "O Yaroh Yiyareh" last, to teach that if he died from the fall, they were Yotzei (without stoning him). There is no need to teach that if he died through stoning, they were Yotzei.
The current Pasuk is not discussing Misas Beis Din. Refer to 19:13:152:4 .
Rashi writes that "O Yaroh Yiyareh" teaches us that someone who is stoned is cast down. Why does the Torah then write "O," seeing as casting down is mandatory - and if that does not kill him, they stone him?
Riva: We find that "O" is sometimes synonymous with 'Asher' (that). 1
Refer to 19:13:151:3.
Hadar Zekenim: Here, "O" is synonuymous with 'Im' (if) - he is stoned if (provided) he was cast down first.
Targum Yonasan: He will be stoned from bi'Yedei Shamayim with hailstones, or arrows of fire will be thrown at him.
Riva: See for example in Parshas Mishpatim, "v'Higisho El ha'Deles, O El ha'Mezuzah" (21:6), and which Targum Yerushalmi translates as ' ... to the door that is attached to the door-post.'