Hadith 5: Religious innovation البدعة
Aisha reported: The Messenger of Allah, peace be upon him, said:
مَنْ أَحْدَثَ فِي أَمْرِنَا هَذَا مَا لَيْسَ فِيهِ فَهُوَ رَدٌّ
Whoever innovates into this matter of ours that which does not belong to it, it will be rejected.
Source: Ṣaḥīḥ al-Bukhārī 2550, Grade: Muttafaqun Alayhi
In another narration, the Prophet said:
مَنْ عَمِلَ عَمَلًا لَيْسَ عَلَيْهِ أَمْرُنَا فَهُوَ رَدٌّ
Whoever performs a deed that is not in accordance with our matter will have it rejected.
Source: Ṣaḥīḥ Muslim 1718, Grade: Sahih