Simak bin Harb narrates from Tamim bin Tarafah that the enemy seized the she-camel of a Muslim man, and a Muslim bought that she-camel; then its owner recognised it. The dispute came before the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) ruled: "Pay him back the price for which he bought it, or leave your she-camel."
Imam al-Shafi'i (may Allah have mercy on him) said: Tamim bin Tarafah did not hear anything from the Prophet (peace and blessings be upon him), and a mursal hadith is not proof, since it is not even known from whom he took it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18254