Achor

trouble, a valley near Jericho, so called in consequence of the
trouble which the sin of Achan caused Israel (Josh. 7:24,26).
The expression "valley of Achor" probably became proverbial for
that which caused trouble, and when Isaiah (Isa. 65:10) refers
to it he uses it in this sense: "The valley of Achor, a place
for herds to lie down in;" i.e., that which had been a source of
calamity would become a source of blessing. Hosea also (Hos.
2:15) uses the expression in the same sense: "The valley of
Achor for a door of hope;" i.e., trouble would be turned into
joy, despair into hope. This valley has been identified with the
Wady Kelt.