كتاب الإيمان
1
The Book of Faith
(5)
Chapter: Clarifying the pillars of Islam and its grand supports
(5)
باب بَيَانِ أَرْكَانِ الْإِسْلَامِ وَدَعَائِمِهِ الْعِظَامِ
Sahih Muslim 16 a

It is narrated on the authority of ('Abdullah) son of Umar (may Allah be pleased with them) that the Prophet (may peace of Allah be upon him) said:

(The superstructure of) al-Islam is raised on five (pillars), i. e. the oneness of Allah, the establishment of prayer, payment of Zakat, the, fast of Ramadan, Pilgrimage (to Mecca). A person said (to 'Abdullah b. Umar the narrator): Which of the two precedes the other-Pilgrimage or the fasts of Rarnadan? Upon this he (the narrator) replied: No (it is not the Pilgrimage first) but the fasts of Ramadan precede the Pilgrimage.
حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ نُمَيْرٍ الْهَمْدَانِيُّ، حَدَّثَنَا أَبُو خَالِدٍ، - يَعْنِي سُلَيْمَانَ بْنَ حَيَّانَ الأَحْمَرَ - عَنْ أَبِي مَالِكٍ الأَشْجَعِيِّ، عَنْ سَعْدِ بْنِ عُبَيْدَةَ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ بُنِيَ الإِسْلاَمُ عَلَى خَمْسَةٍ عَلَى أَنْ يُوَحَّدَ اللَّهُ وَإِقَامِ الصَّلاَةِ وَإِيتَاءِ الزَّكَاةِ وَصِيَامِ رَمَضَانَ وَالْحَجِّ ‏"‏ ‏.‏ فَقَالَ رَجُلٌ الْحَجِّ وَصِيَامِ رَمَضَانَ قَالَ لاَ ‏.‏ صِيَامِ رَمَضَانَ وَالْحَجِّ ‏.‏ هَكَذَا سَمِعْتُهُ مِنْ رَسُولِ اللَّهِ صلى الله عليه وسلم ‏.‏
Reference : Sahih Muslim 16 a
In-book reference : Book 1, Hadith 19
USC-MSA web (English) reference : Book 1, Hadith 18
  (deprecated numbering scheme)