Ibn Umar heard a man swearing: No, I swear by the Ka'bah. Ibn Umar said to him: I heard the Messenger of Allah (ﷺ) say: He who swears by anyone but Allah is polytheist.
Hadith Commentary: Oaths and Vows (Kitab Al-Aiman Wa Al-Nudhur)
This narration from Sunan Abi Dawud 3251 contains profound legal and theological implications regarding the sanctity of oaths in Islam.
The Prohibition Explained
The prohibition stems from the fundamental Islamic principle of Tawhid (monotheism). Swearing by other than Allah constitutes shirk (polytheism) because it attributes divine sanctity to created beings or objects.
The Ka'bah, while sacred as the House of Allah, remains a created entity and cannot bear the weight of oaths reserved for the Creator alone.
Scholarly Interpretation
Classical scholars classify this as minor shirk (shirk asghar) that does not expel one from Islam but remains a grave sin requiring repentance.
Imam An-Nawawi explains that such oaths are invalid and prohibited, even if the intention was to emphasize the seriousness of one's statement.
Proper Oath Formulation
The correct Islamic oath must be sworn exclusively by Allah's names or attributes, such as "Wallahi" (By Allah) or "Wa'azmati Allah" (By Allah's majesty).
Ibn Umar's immediate correction demonstrates the Companions' vigilance in preserving pure monotheism and educating Muslims in proper religious practice.