Narrated Ibn Umar: Allah's apostle said: Islam is based on (the following) five (principles):
- To testify that none has the right to be worshipped but Allah and Muhammad is Allah's apostle.
- To offer the (compulsory congregational) prayers dutifully and perfectly.
- To pay Zakat (i.e. obligatory charity).
- To perform Hajj (i.e. Pilgrimage to Mecca).
- To observe fast during the month of Ramadan.
(Sahih al-Bukhari, Vol. 1, p. 17).