Albert Barnes Commentary Joshua 6:17

"And the city shall be devoted, even it and all that is therein, to Jehovah: only Rahab the harlot shall live, she and all that are with her in the house, because she hid the messengers that we sent." — Joshua 6:17 (ASV)

Accursed - Better, as in the margin, ('devoted' (see the note on Leviticus 27:28)). In other cases, only the inhabitants of the towns were killed; their cattle and property became the plunder of the victors.

But Jericho, as the first Canaanite city to be captured, was devoted by Israel as first-fruits to God, as a sign that Israel received all the land from Him. Every living thing was put to death (Rahab and her household excepted) as a sacrifice to God, and the indestructible goods were brought into the treasury of the sanctuary (Joshua 6:19).