Narrated 'Abdullah bin 'Abbas: I was informed by Abu Sufyan that Heraclius said to him, "I asked you whether they (followers of Muhammad) were increasing or decreasing. You replied that they were increasing. And in fact, this is the way of true Faith till it is complete in all respects. I further asked you whether there was anybody, who, after embracing his (the Prophets) religion (Islam) became displeased and discarded it. You replied in the negative, and in fact, this is (a sign of) true faith. When its delight enters the heart and mixes with them completely, nobody can be displeased with it."

Narrated Ibn 'Umar: Allah's Apostle 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 Apostle. 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.