(35) باب بَيَانِ إِطْلاَقِ اسْمِ الْكُفْرِ عَلَى مَنْ تَرَكَ الصَّلاَةَ
It is narrated on the authority of Jabir that he heard the Apostle (may peace and blessings be upon him) saying. Verily between man and between polytheism and unbelief is the negligence of prayer.
Reference: Sahih Muslim 82 a
In-book reference: Book 1, Hadith 153
USC-MSA web (English) reference(deprecated numbering scheme): Book 1, Hadith 146