Joshua 15:15

And he went up thence to the inhabitants of Debir: and the name of Debir before was Kirjath–sepher.

Cross-reference

Joshua 15:49 lists Debir (Kiriath-sannah) as a Judahite city — confirming the same location.

Joshua 10:38 describes Joshua's conquest of the city Debir, the same city Caleb later attacked.

Judges 1:11-13 gives the same account of Caleb's offer to capture Debir — a parallel narrative.