Fourth pillar of Islam, fasting was prescribed in the month of Chaban in the year 2 of the Hegira. It is a worship which is part of what scholars call (malummina ad-din bi-d-darura), in other words things known in a sure and certain way as a principle of religion. Fasting is legally based on the Quran, Sunnah and community consensus.

The Arabic term sawm means to abstain. We find this meaning in the Koran when Myriam, after giving birth to Issa, took a vow of silence: "I made a vow of sawm (fasting) to the All-Merciful: I will therefore not speak today to any human being" - Sura 19, verse 26, that is to say: I will not speak to anyone and will observe silence. In Islamic terminology, sawm means giving up food, drink and carnal intercourse from dawn to dusk.