1)
Who sent his hand?
1.
Rashi: Achitofel the Rasha.
2)
Who are "bi'Shlomav"?
1.
Rashi: With one who was serene and at peace with him 1 . Radak - this is like 'b'Ish Shlomav'; Ish is omitted. Also "va'Ani Sefilah" (109:4) is like va'Ani Ish Sefilah.
2.
Radak: "Bi'Shlomav" is [against] David and his followers, who were at peace with Achitofel.
1
Malbim: He wanted to chase David and kill him with his own hands.
3)
What Bris did he annul?
1.
Radak, Malbim: It is the Bris that he had with David.
