Bulugh al-Maram 1375
In a narration which is Marfu' (attributed to the Prophet) reported by Abu Dawud and an-Nasa'i from Abu Hurairah (RA) it has:
"Do not swear by your fathers, nor by your mothers, nor by the rivals (set up as equals with Allah); and do not swear by Allah except when you are speaking the truth."
وَفِي رِوَايَةٍ لِأَبِي دَاوُدَ, وَالنَّسَائِيِّ: عَنْ أَبِي هُرَيْرَةَ ‏- رضى الله عنه ‏- { لَا تَحْلِفُوا بِآبَائِكُمْ, وَلَا بِأُمَّهَاتِكُمْ, وَلَا بِالْأَنْدَادِ, وَلَا تَحْلِفُوا إِلَّا بِاَللَّهِ, وَلَا تَحْلِفُوا بِاَللَّهِ إِلَّا وَأَنْتُمْ صَادِقُونَ" }   1‏ .‏‏1 ‏- صحيح.‏ رواه أبو داود ( 3248 )‏، والنسائي ( 7 / 5 )‏.‏