Hadith 1:5
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 Muslimit 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 ، وَفِي رِوَايَةٍ :مَنْ عَمِلَ عَمَلًا لَيْسَ عَلَيْهِ أَمْرُنَا فَهُوَ رَدٌّ"
Original Reference: 40 Hadith Nawawi 5