It is narrated on the authority of 'Abdullah son of 'Umar that the Messenger of Allah ﷺ said: (The superstructure of) al-Islam is raised on five (pillars), testifying (the fact) that there is no god but Allah, that Muhammad is His bondsman and messenger, and the establishment of prayer, payment of Zakat, Pilgrimage to the House (Ka'ba) and the fast of Ramadan.

حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُعَاذٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا عَاصِمٌ، - وَهُوَ ابْنُ مُحَمَّدِ بْنِ زَيْدِ بْنِ عَبْدِ اللَّهِ بْنِ عُمَرَ - عَنْ أَبِيهِ، قَالَ قَالَ عَبْدُ اللَّهِ قَالَ رَسُولُ اللَّهِ ﷺ
" بُنِيَ الإِسْلاَمُ عَلَى خَمْسٍ شَهَادَةِ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ وَأَنَّ مُحَمَّدًا عَبْدُهُ وَرَسُولُهُ وَإِقَامِ الصَّلاَةِ وَإِيتَاءِ الزَّكَاةِ وَحَجِّ الْبَيْتِ وَصَوْمِ رَمَضَانَ " .