Ibn Umar reported: The Messenger of Allah, peace and blessings be upon him, said:
Islam is built upon five: to worship Allah (God) and to disbelieve in what is worshiped besides him, to establish prayer, to give charity, to perform Hajj pilgrimage to the House, and to fast the month of Ramadan.
Source: Sahih Bukhari 8, Grade: Muttafaqun Alayhi
