Did Shmuel say so aloud?
Rashi: He said so in his heart, that he is proper for kingship.
Radak: Perhaps he said so aloud.
What is the meaning of "Neged Hashem Meshicho"?
Radak: He thought that Hashem will pick only someone beautiful and tall like Sha'ul, so people will fear him. However, his heart must be good and straight. "Neged Hashem Meshicho" is like "Nochach Hashem Darkechem" (Shoftim 18:6), i.e. Hashem will be with him.
Radak citing Targum Yonasan: Hashem's anointed is prepared in front of Him.
Radak (7), Malbim: He thought that Hashem will pick only someone like Sha'ul. There was no one else in Yisrael like Sha'ul; others reached only until his shoulder (9:2)! Therefore, Meshicho (Sha'ul) is still Neged Hashem (king) until someone else like him will be found. Shmuel claimed that due to this, Sha'ul should not be deposed. 1 Malbim - also, when he saw Eli'av and Hashem did not say to anoint him, he understood that Hashem does not desire him
Hashem told Shmuel to go to Beis Lechem to anoint a son of Yishai to be king! Radak and Malbim (15:28) explained that Shmuel told Sha'ul that his kingship was irrevocably torn away! Also, why did Hashem need to say (verse 7) that He sees the heart? Shmuel knew that Sha'ul was deposed due to his sin! This requires investigation. (PF)
Why did Shmuel think that Eli'av will or will not be king?
Radak: He was the Bechor, and he was beautiful and tall like Sha'ul. He thought that Hashem picks such people for kings, so the people will fear them. Indeed, this is correct - as long as his heart is good and straight.
Radak (7), Malbim: He will not be king, for he was not beautiful and tall like Sha'ul. Refer to 16:6:2:3.
