What renders digging permissible even if intended for personal use or public benefit in a public thoroughfare?

Primary text

If the residents of the path agree to the digging in exchange for compensation (iqad), it becomes permissible. This applies whether the well is dug for oneself (for rainwater drainage from a house or drawing personal water) or for public charity (sabil) and the road's benefit. This principle also applies if the action is taken on the property of a specific individual.