The Literal Commandment
When the LORD your God brings you into the land where you are entering to possess it, and clears away many nations before you, the Hittites and the Girgashites and the Amorites and the Canaanites and the Perizzites and the Hivites and the Jebusites, seven nations greater and stronger than you, and when the LORD your God delivers them before you and you defeat them, then you shall utterly destroy them. You shall make no covenant with them and show no favor to them. (Deuteronomy 7:1-2)
The literal commandment is that we should show no favor to idolaters.
The word "favor" in this verse is translated from a Hebrew word [chanan] that means "grace". This same word is used in the Aaronic benediction from Numbers 6:
"Speak to Aaron and to his sons, saying, 'Thus you shall bless the sons of Israel. You shall say to them:
The LORD bless you, and keep you;
The LORD make His face shine on you, And be gracious to you;
The LORD lift up His countenance on you, And give you peace.'
So they shall invoke My name on the sons of Israel, and I then will bless them." (Numbers 6:23-27)