עַתָּה֩ לֵ֨ךְ וְהִכִּֽיתָ֜ה אֶת־עֲמָלֵ֗ק וְהַֽחֲרַמְתֶּם֙ אֶת־כָּל־אֲשֶׁר־ל֔וֹ וְלֹ֥א תַחְמֹ֖ל עָלָ֑יו וְהֵמַתָּ֞ה מֵאִ֣ישׁ עַד־אִשָּׁ֗ה מֵֽעֹלֵל֙ וְעַד־יוֹנֵ֔ק מִשּׁ֣וֹר וְעַד־שֶׂ֔ה מִגָּמָ֖ל וְעַד־חֲמֽוֹר׃ (ס)
지금 가서 아말렉을 쳐서 그들의 모든 소유를 남기지 말고 진멸하되 남녀와 소아와 젖먹는 아이와 우양과 약대와 나귀를 죽이라 하셨나이다
Rashi
Oxen and sheep. They were sorcerers, and they would change themselves to appear as animals.2 Radak suggests another reason for destroying the animals. The Torah specifies that the memory of Amoleik should be erased. Therefore, Shmuel instructed that not even an ox or a sheep should remain about which one might say ‘this animal belonged to Amoleik.’
Tze'enah Ure'enah
“Now go” [15:3]. Now, you, Saul, should go and kill and destroy Amalek and have no pity, not even on the oxen, donkeys, sheep, or nursing children. Our sages say that there were many among Amalek who made themselves to appear as sheep, by magical means, in the expectation that they would not be recognized and they would be left alive. Therefore, the Holy One commanded that you should even kill the sheep.3Rashi, I Samuel, 15:3.