Why did he say "Li Diber Tzur Yisrael"?
Rashi: Tzur Yisrael spoke to me and commanded me [to be a Moshel
What is "Moshel ba'Adam"?
Rashi (from Yevamos 61a): [Hashem commanded that I] rule over Yisrael, who are called Adam - "Adam Atem" (Yechezkel 34:31).
Rashi citing Mo'ed Katan 15b: It is Hashem - and He told me that a Tzadik 'rules' over Him. He decrees, and a Tzadik nullifies His decree!
Malbim: [Melech ha'Mashi'ach] will rule over all men.
Why does it say "Tzadik Moshel Yir'as Elokim"?
Rashi: [Hashem commanded that I] be a righteous ruler and fear Him.
Refer to 22:3:2:2.
Radak: Hashem made me king on condition that my kingship be with Yir'as Elokim, and I will be a Tzadik.
Radak based on Targum Yonasan: Melech ha'Mashi'ach will descend from me; he will rule with Yir'as Elokim.
Malbim: [Melech ha'Mashi'ach will merit to rule over all men because] he has a Ru'ach or Yir'as Elokim to rule over himself. This is like the Chacham said to Melech ha'Kuzari - one who rules over himself is proper to rule over the Klal.
