Abu Dawud
Oaths and Vows
Book Number: 015 / Hadith Number: 3245
Narated By Abdullah ibn Umar : Sa'id ibn Ubaydah said: Ibn Umar heard a man swearing: No, I swear by the Ka'bah. Ibn Umar said to him: I heard the Apostle of Allah (pbuh) say: He who swears by anyone but Allah is polytheist.