Why did he say that he is "Imcha"?
Radak #1: Even though he is from Shevet Binyamin, he is under your jurisdiction to kill him.
Radak #2: [Mahari Kara - Arrange that] he is always with you [in Yerushalayim], so you can find a reason to kill him.
Radak citing Brachos 8a: He was Shlomo's Rebbi and taught him.
Malbim citing Mahari: He is among your counselors; he was Shlomo's Rebbi. You should distance him, for his deeds are evil!
What is the meaning of "Kilelani"?
Radak: He disgraced me verbally and in action. He threw [rocks and] earth at David and his men (Shmuel II, 16:13).
What is "Nimretzes"?
Rashi: It is explicit, like "Mah Yamritzecha" and "u'Mah Nimretzu" (Iyov 15:3, 6:25); the latter is like "Mah Nimletzu" (Tehilim 119:103).
Radak: It is strong - he said "Ish ha'Damim Ish ha'Beliya'al" (Shmuel II, 16:7).
Radak citing Shabbos 105a: NiMReTZeS is an acronym for [saying that David is] No'ef (an adulterer), Mo'avi (forbidden to marry a Bas Yisrael, for he descends from Rus ha'Mo'aviyah), Rotze'ach (for causing the death of Uriyah), TZorer (one who causes pain), and To'evah (abomination).
Why did he come to greet David?
Radak: He asked me to pardon him.
Malbim: He forced me to swear to him (not to kill him). He said "I was first of all Beis Yosef to come to you." This was quite brazen!
Why did David command to return good, to Barzilai's children, in between his command to punish Yo'av and Shim'i? Barzilai helped David after Shim'i cursed him!
Perhaps David wanted to separate the punishments that Shlomo must inflict, just like the Torah separates punishments (refer to Bamidbar 10:35:3:1. - PF)
