Sayyiduna Ubadah bin al-Samit (may Allah be pleased with him) says that the Prophet (peace and blessings be upon him) gave the judgement: "La darar wa la dirar: do not cause harm, and do not harm anyone in retaliation."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب إحياء الموات / 11877