Since the landlord was involved in this, it is his landlord who would have to pay him, not you. If he didn't have a contract with his landlord then even his landlord most likely, doesn't have to pay. I would speak with the neighbor either in person or by phone and respectfully explain to him that it is not your responsibility to pay him. That it is his landlords responsibility and to take the matter up with her/him. He really can't do anything to you legally so if he tried to make waves, I'd make him aware of that then wash your hands of the matter.