عَنْ عَائِشَةَ قَالَتْ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنْ أَحْدَثَ فِي أَمْرِنَا هَذَا مَا لَيْسَ مِنْهُ فَهُوَ رد»
‘A’isha reported God’s messenger as saying, “If anyone introduces into this affair of ours anything which does not belong to it, it is rejected.”
(Bukhari and Muslim.)