Language:
الأربعون النووية
Forty Hadith of an-Nawawi
Hadith 5, 40 Hadith an-Nawawi

On the authority of the mother of the faithful, Aisha (ra), who said:

The Messenger of Allah (ﷺ) said, “He who innovates something in this matter of ours (i.e., Islam) that is not of it will have it rejected (by Allah).” [Bukhari & Muslim] In another version in Muslim it reads: “He who does an act which we have not commanded, will have it rejected (by Allah).”

عَنْ أُمِّ الْمُؤْمِنِينَ أُمِّ عَبْدِ اللَّهِ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا، قَالَتْ: قَالَ: رَسُولُ اللَّهِ صلى الله عليه و سلم "مَنْ أَحْدَثَ فِي أَمْرِنَا هَذَا مَا لَيْسَ مِنْهُ فَهُوَ رَدٌّ [رَوَاهُ الْبُخَارِيُّ] ،[وَمُسْلِمٌ] وَفِي رِوَايَةٍ لِمُسْلِمٍ: مَنْ عَمِلَ عَمَلًا لَيْسَ عَلَيْهِ أَمْرُنَا فَهُوَ رَدٌّ".
Reference : Hadith 5, 40 Hadith an-Nawawi