“your eye must not pity them.” A Semitic idiom that means, “you are not to pity them.” In the culture, the “eye” reflected the character or attitude of the person, so for a person’s eye to pity someone was for the person to have an attitude of pity, which would then lead to having mercy and sparing the people. God’s command seems harsh, but God knew the hearts of the Canaanites, and we know the history of Israel. Israel did not obey God and thus did not destroy all the Canaanites. But the Canaanites did not become thankful and so convert to believing in Yahweh. Instead, the Canaanites led the Israelites into idol worship which led to misery and slavery for Israel and certainly everlasting death for many Israelites, who favored Baal and the other Canaanite gods over Yahweh and thus did not attain salvation.

[For more on idioms involving the eye, see commentary on Proverbs 22:9.]