This is what the LORD of heavenly forces says: I am going to punish the Amalekites for what they did to Israel: how they attacked the Israelites as they came up from Egypt.
So go! Attack the Amalekites; put everything that belongs to them under the ban. Spare no one. Kill men and women, children and infants, oxen and sheep, camels and donkeys."
References for 1 Samuel 15:3