(4) باب التَّشْدِيدِ فِي الْحَلِفِ بِغَيْرِ اللَّهِ تَعَالَى
It was narrated that Ibn 'Umar said:
"The Messenger of Allah said: 'Whoever swears, let him not swear by anything other than Allah.'" The Quraish used to swear by their forefathers, and so he said: "Do not swear by your forefathers." (ID)
Reference (ID): Sunan an-Nasa'i 3764 (ID)
In-book reference (ID): Book 35, Hadith 4 (ID)
English translation (ID): Vol. 4, Book 35, Hadith 3795 (ID)