It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "A vow is valid only in that in which Allah is obeyed; there is no vow in severing ties of kinship; and there is no divorce and no freeing of a slave in respect of what one does not own."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10887