The statement of the Prophet (saws) Islam is based on five principles

Narrated Ibn 'Umar: Allah's Messenger (sallallahu 'alaihi wa sallam) said: Islam is based on (the following) five (principles): 

1. To testify that none has the right to be worshipped but Allah and Muhammad is Allah's Messenger (sallallahu 'alaihi wa sallam). 

2. To offer the (compulsory congregational) prayers dutifully and perfectly. 

3. To pay Zakat (i.e. obligatory charity) . 

4. To perform Hajj. (i.e. Pilgrimage to Mecca) 

5. To observe fast during the month of Ramadan.

Source: http://www.hadithbd.com/hadith/link/?id=9