Musannaf Ibn Abi Shaybah 32402 — Book of Faith

Ja'far bin Burqan said: Umar bin Abd al-Aziz (may Allah have mercy on him) wrote to us, saying: "After praise and blessings: indeed, the firmness of the religion and the foundation of Islam are faith in Allah, keeping up the prayers and giving zakah. So perform the prayer at its proper time."