Hadith
The Prophet ﷺ said: “Indeed, between a person and shirk (idolatry) and kufr (disbelief) lies the leaving of Salah (Namaz).”
عَنْ جَابِرٍ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ إِنَّ بَيْنَ الرَّجُلِ وَبَيْنَ الشِّرْكِ وَالْكُفْرِ تَرْكَ الصَّلَاةِ
Sahih Muslim 82
Ponder This Hadith
Scholars clarify that this hadith does not refer to one who neglects the prayer out of laziness, forgetfulness, or occasional carelessness. Rather, it applies to the one who does not believe the five daily Salah are obligatory upon him at all.
It is worth reflecting upon this: if Ismailis do not fall into this category, then who does?