Sayyiduna Kardam bin Qays (may Allah be pleased with him) narrated: I said: "O Messenger of Allah! I vowed that I would sacrifice a camel at such-and-such a place." The Prophet (peace and blessings be upon him) said: "Fulfil your vow; but a vow concerning cutting off ties of kinship has no standing, nor does a vow concerning what a person does not own."
Imam al-Tabarani recorded it within a long hadith that will come later in the chapter on marriage, in sha' Allah; its chain contains a narrator whom I do not know.