What is the meaning of "Matziv Lo Yad"?
Rashi: He is building a Mizbe'ach. Eliyahu fixed it later - "va'Yerapei Es Mizbach Hashem he'Harus" (Melachim 1 18:30).
Rashi citing Targum Yonasan: He is preparing a place to divide the spoils 1 [Radak - and for the soldiers to rest].
Chomas Anach: Shmuel knew [via Ru'ach ha'Kodesh] that Sha'ul is keeping alive "Yad Al Kes Kah" (Shemos 17:16), i.e. Agag and the animals from Amalek.
Malbim: He marked the place of the victory with the form of a hand, a sign of the strong hand that He 2 showed in this war.
This implies that other spoils of Amalek [other than animals] were permitted; Refer to 15:3:5:1,2 and the notes there. Alternatively, they were dividing up the animals for the soldiers to offer them as Korbanos. (PF)
Surely, he refers to Hashem's strong hand. This is why they wanted to offer Korbanos to Him. Also, if Sha'ul intended for his own hand, Hashem should have rebuked him also for this! (PF)
Who went to Gilgal?
Radak, Malbim: Sha'ul did, after [he prepared a place, Mizbe'ach or marker in] Karmel, to sacrifice in Gilgal.
Why did he go to Gilgal?
Radak: This is where the Aron and Ohel Mo'ed were initially when Yisrael entered the land. They honored the [initial] place of the Aron and Ohel Mo'ed in Gilgal, even though now they are in Nov, and sacrificed there when Bamos were permitted. That is where they renewed the kingship (11:14, 15).
