Why did he say "the kingship was mine"?
Malbim: (a) I should have become king because I was the oldest [living son]. (b) The nation agreed [that I be king] - "v'Alai Samu Chol Yisrael 1 Peneihem." Since it was removed, it is proper to give to me a small matter of kingship. Even though a commoner may not use a king's scepter [or other matters of his], I am not a commoner, for initially kingship came to me!
Adoniyahu invited Bnei Yehudah to declare him king. We do not find that the other Shevatim wanted him! It seems that Adoniyahu was not so meticulous to say only the truth. (PF)
What is the meaning of "Ki me'Hashem Haysah Lo"?
Radak: It was known that Nasan ha'Navi said Al Pi Hashem that Shlomo will be king. Metzudas David - if so, who would be so foolish to contest Shlomo's kingship 1 ?! (I.e. I request Avishag only for her beauty.)
Malbim: The Isur for a commoner to use a king's scepter is only for a king who rules based on the nation's choice. He is really a commoner, so we need rules of honor to distinguish him from others. When Hashem chooses the king, there is no need for rules of honor to distinguish him!
Radak: Even so, Adoniyahu would contest it if he could. (He did not tell her this. Rather, Radak explains that he requested Avishag in order to contest the kingship, even though he himself admitted that Hashem gave it to Shlomo! - PF)
