Hadith No. 3

Abu Abdur-Rahman Abdullah bin Umar bin Al-Khattab (may Allah be pleased with him) narrated, "I heard the Messenger of Allah (peace be upon him) saying, Islam is based on five (pillars): testifying that there is no god but Allah and that Muhammad is His Messenger, offering the prayer, paying Zakah, performing Hajj and observing the fast (during the month) of Ramadan.`" Recorded by Al-Bukhary and Muslim)