Commentary for I Samuel 15:5

And he fought in the valley. [Meaning the same as] וַיִלָּחֵם בַּנַּחַל [=and he fought in the valley]. Our Rabbis said, concerning the valley, he argued and concluded, that if for the sake of one life, the Torah said to decapitate a calf in the valley,⁷See Devarim 21:4. how much more for the sake of all these lives.⁸Shaul rationalized that he will spare the animals to use as sacrifices to atone for the Amoleikites that were killed. For additional arguments presented by Shaul and their consequences, see Maseches Yoma 22b. If man has sinned, what have the animals sinned?