(5) باب بَيَانِ أَرْكَانِ الْإِسْلَامِ وَدَعَائِمِهِ الْعِظَامِ
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.
Reference: Sahih Muslim 16 a
In-book reference: Book 1, Hadith 19
USC-MSA web (English) reference(deprecated numbering scheme): Book 1, Hadith 18