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]‏ .‏