Sayyiduna Tha'labah bin al-Hakam (may Allah be pleased with him) narrates: On the day of Khaybar we got some sheep and goats, and the people plundered them. Then the Prophet (peace and blessings be upon him) came and saw that their cooking pots were boiling. He (peace and blessings be upon him) said: "What is this?" They said: O Messenger of Allah, it is plunder. He (peace and blessings be upon him) said: "Overturn them, for plunder is not lawful." So they overturned whatever remained in them.
Hadith Referenceالمعجم الكبير للطبراني / باب الثاء / 1358