Wikipedia
Nanawatai ( Pashto: ننواتی, "sanctuary") is a tenet of the Pashtunwali code of the Pashtun people. It allows a beleaguered person to enter the house of any other person and make a request of him which cannot be refused, even at the cost of the host's own life or fortune. A similar code of conduct is used by the neighbouring Baluch people.
Traditionally it is used to refer to a request for sanctuary, whereby the host must be willing to fight or die for the sake of anyone who comes knocking at his door seeking refuge, even if it is a sworn enemy.
As the burden of sanctuary and protection extends even to fighting against government troops on behalf of the person seeking refuge, some have suggested that Mullah Omar's refusal to turn in Osama bin Laden was due only to his having availed himself of nanawatai.