carved in stone

idiomPart ofcarve

carved in stone — idiom

1. fixed and unable to be changed, especially of rules, plans, or agreements.

1.idiom
Definition

fixed and unable to be changed, especially of rules, plans, or agreements.

Example

The deadline isn't carved in stone — we can ask for an extension if we need one.

Her decision to move abroad was not carved in stone, so her friends kept hoping she would stay.