Sahih Muslim 16
Sahih Muslim · Book 1: The Book of Faith · Clarifying the pillars of Islam and its grand supports
It is reported on the authority of Ta'us that a man said to 'Abdullah son of 'Umar (may Allah be pleased with him). Why don't you carry out a military expedition? Upon which he replied:
وَحَدَّثَنِي ابْنُ نُمَيْرٍ ، حَدَّثَنَا أَبِي ، حَدَّثَنَا حَنْظَلَةُ ، قَالَ سَمِعْتُ عِكْرِمَةَ بْنَ خَالِدٍ ، يُحَدِّثُ طَاوُسًا أَنَّ رَجُلاً، قَالَ لِعَبْدِ اللَّهِ بْنِ عُمَرَ أَلاَ تَغْزُو فَقَالَ إِنِّي سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ " إِنَّ الإِسْلاَمَ بُنِيَ عَلَى خَمْسٍ شَهَادَةِ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ وَإِقَامِ الصَّلاَةِ وَإِيتَاءِ الزَّكَاةِ وَصِيَامِ رَمَضَانَ وَحَجِّ الْبَيْتِ " .
I heard the messenger of Allah (ﷺ) say: Verily, al-Islam is founded on five (pillars): testifying the fact that there is no god but Allah, establishment of prayer, payment of Zakat, fast of Ramadan and Pilgrimage to the House.