Sahih Muslim — The Book of Faith — Hadith No: 112
وَحَدَّثَنَا سَهْلُ بْنُ عُثْمَانَ الْعَسْكَرِيُّ، حَدَّثَنَا يَحْيَى بْنُ زَكَرِيَّاءَ، حَدَّثَنَا سَعْدُ بْنُ طَارِقٍ، قَالَ حَدَّثَنِي سَعْدُ بْنُ عُبَيْدَةَ السُّلَمِيُّ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " بُنِيَ الإِسْلاَمُ عَلَى خَمْسٍ عَلَى أَنْ يُعْبَدَ اللَّهُ وَيُكْفَرَ بِمَا دُونَهُ وَإِقَامِ الصَّلاَةِ وَإِيتَاءِ الزَّكَاةِ وَحَجِّ الْبَيْتِ وَصَوْمِ رَمَضَانَ " .
Translation
It is narrated on the authority of ('Abdullah) son of 'Umar, that the Prophet (may peace of Allah be upon him) said:(The superstructure of) al-Islam is raised on five (pillars), i. e. Allah (alone) should be worshipped, and (all other gods) beside Him should be (categorically) denied. Establishment of prayer, the payment of Zakat, Pilgrimage to the House, and the fast of Ramadan (are the other obligatory acts besides the belief in the oneness of Allah and denial of all other gods)