The ruling on praying in a direction other than the qiblah

May Allah reward you for your work : A man prayed the obligatory prayer outside his city, and he prayed in a direction other than the qiblah, knowing that he had asked about the correct direction and been shown it, but it became difficult for him when he changed the room in which he had asked.
He must repeat his prayer. If he was traveling—and that is what appears to be the case—he must repeat it shortened. If he was a resident, he must repeat it in full.