Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrated that a man came to the Messenger of Allah (peace and blessings be upon him) seeking a ruling (fatwa) from him; he had made a sacrificial camel (badanah) binding upon himself in an oath he had sworn. So he (peace and blessings be upon him) gave him the ruling (to give) a she-camel from among the camels, and sternly forbade the man from doing so again.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10654