Why did he say "ha'Rosh Kelev Anochi"?
Rashi #1: Am I as esteemed even like the head guardian of David's dogs?!
Rashi #2: Based on the Nekudos (note) under ha'Rosh (Pashta, a minor pause) and Kelev Anochi are connected with a Makaf 1 - do I desire to be a head in your house? It is better that I be a dog and a commoner in David's house!
Radak: He mocks. If I were the head of the dogs, i.e. even if I were appointed only over the dogs, I would be called the head dog. Further, even for Shevet Yehudah, which you hate, if I had any appointment over them, you should not disgrace me so much.
Malbim: It is proper that a king guard the honor even of his minor officers, since they are faithful to him and serve him, and to show honor to a head general due to his level, even if he is the head general rule of his enemy. All the more so, the head general of his own army, he should guard his honor for both reasons. You disgrace me as if I have both shortcomings, i.e. head of the dogs (low people), and of Yehudah.
Minchas Shai: This is unlike most Seforim. (Rashi says that Yonason translates like this; our text of Yonason does not - PF.)
Why did he say "ha'Yom E'eseh Chesed
Radak: Was I obligated to do Chesed with Beis Sha'ul, that [you show no appreciation, rather,] you disgraced me?! I did great Chesed with your father's house until now. I established [you] to be king, and I did not give you over into David's hands - and you accuse me of sinning with this woman?!
Radak citing Targum Yonasan: From now, I will be a commoner in the remnant of Beis David.
Malbim: You were foolish. You should have borne this in your heart until you do not need me and do not fear me. Today, (a) you need me, that I will do Chesed with your father's house, and (b) you should fear me, that I not give you over into David's hands. You are in my hands like clay in the potter's hands!
