Sayyiduna Ali (may Allah be pleased with him) narrated: A man came to the Prophet (peace and blessings be upon him) and said: "I have vowed that I will sacrifice my she-camel and do such-and-such." The Prophet (peace and blessings be upon him) said: "As for your she-camel, sacrifice her; as for such-and-such, that is from Shaytan."
Imam Ahmad recorded it; its chain contains a narrator, Jabir al-Ju'fi, who is da'if (weak), though Shu'bah and al-Thawri declared him thiqah (trustworthy).