Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) says: Whoever does not offer the prayer has no religion.
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains Abu Nu'aym Dirar bin Surad, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 1637