1)
Why does it say "at that time"?
1.
Malbim: Due to the Nevu'ah he heard from Achiyah ha'Shiloni, he had the audacity to rebel.
2)
Why is he called "ha'Shiloni"?
1.
Radak: He was from Shilo. One from Shilo is called Shiloni; one from Gilah is called Giloni.
3)
Who was covered with a new garment ?
1.
Radak: The verse is not clear, whether it was Achiyah or Yaravam. Rav and Levi argued about this (Rus Rabah 7:2). Shmuel said, presumably, it was Achiyah, for Tzadikim normally tear [their own garments] due to division of Beis David.
