1. Hadith: 'Abdullah Ibne-'Umar Radiyallahu 'anhuma narrates that Rasullullah Sallallahu 'alaihi wasallam said: Islam has been built upon five pillars: 1) To testify that none is worthy of worship but Allah and that Muhammad is the Messenger of Allah, 2) to establish Salat, 3) to give Zakat, 4) to perform Hajj, and 5) to fast (Saum) in Ramadan. (Bukhari: 7)

Allah Subhanahu wa Ta'ala says in The Qur'an (Translation): And establish Salat and give Zakat, and bow with those who bow in worship (i.e. pray in congregation). (Al-Baqarah 2: 43)