Hadith
Aisha reported: The Messenger of Allah, peace and blessings be upon him, said, “Whoever introduces into this matter of ours that which is not from it, it will be rejected.”
عَنْ عَائِشَةَ قَالَتْ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مَنْ أَحْدَثَ فِي أَمْرِنَا هَذَا مَا لَيْسَ فِيهِ فَهُوَ رَدٌّ
Sahih Al-Bukhari 2697, Sahih Muslim 1718
Ponder This Hadith
If the Quran and Sunnah are built upon a defined set of beliefs, and Ismailism is built upon an entirely separate and contradictory framework, would that not mean that its beliefs, practices, and acts of worship fall under what the Prophet ﷺ said would be rejected?