What is the meaning of "Ad ha'Rosh"?
Rashi citing Targum Yonasan: Until the peak of the mountain.
What is the meaning of "Asher Yishtachaveh"?
Rashi: He used to bow there when he came to Yerushalayim. He would see the tent in which the Aron was.
Radak: He went there in order to bow, because he separated from the place of the Mikdash and did not know whether or not he will return. He acted like one who asks permission from his beloved when going into exile.
What is the significance that Chushai ha'Archi came right now?
Malbim (34, b'Sof): Right after David prayed that Hashem thwart Achitofel's counsel, came Chushai, who would do so.
Why is he called "ha'Archi"?
Radak: It is based on his place. It is mentioned in the border of Yosef - "El Gevul ha'Archi Ataros" (Yehoshua 16:2).
Why does it say "Karu'a Kutanto"?
