What spirit came on Amasai?
'Rashi', Radak: It was not prophecy, rather, desire. This prompted him to speak first, before Bnei Binyamin and Yehudah with him. This is like "va'Tehi Al Yiftach Ru'ach Hashem" (Shoftim 11:29).
What were his first words to David?
Malbim: He said "Rosh ha'Shalishim 1 ?" ? i.e. I am the head of these Giborim, and I am to [help] you, for I am your kin and flesh!
Malbim: These words also refer to the previous word ? Amasai was Rosh ha'Shalishim.
Why did he say both "David" and "Ben Yishai"?
Vilna Gaon: It is proper to come to you due to your lineage 1 , and due to your attribute of being Yishai's son.
Perhaps 'lineage' refers to descending from Yehudah, Nachshon and Bo'az. It is an additional attribute to be Ben Yishai, one of the four people who never sinned (Shabbos 55b). (PF)
Why did he say "v'Imcha Ven Yishai"?
'Rashi': We want to be with you and help you!
Malbim: Even though I do not descend from Yishai (his mother Avigayil was only a maternal sister of David), it is as if I am, for he was raised in Yishai's house.
Why did he say "Shalom Lecha v'Shalom l'Ozrecha"?
Malbim: These men are Shalem (fully) with you and those who help you.
David feared lest Bnei Binyamin came to trap him. Why did he put them at the head of the troop?
'Rashi' (17): They took with them Amasai (his sister's son) and other relatives of David to show that they are faithful with him.
Malbim (18): David prayed that if they came to help him, Hashem should put in his heart love for them [and he felt this - PF].
Why did he say "Azarcha Elokecha"?
'Rashi': You do not owe appreciation to us for our help. It is from Hashem!
Malbim: This was after David cut Sha'ul's garment, and [people] saw that Hashem is with David 1 .
I.e. via Hashgachah, Sha'ul needed to relieve himself then, and he picked the cave in which David was, and especially according to the Midrash that a spider rapidly covered the opening with a web, to convince Sha'ul that no one was inside! (PF)
