As-Sawm in the Sharī''ah is to abstain — with intention — from food, drink, and intercourse from the break of true dawn (al-fajr aṣ-ṣādiq) until sunset, throughout the days of Ramadan. It is the fourth pillar of Islam and was made obligatory in the second year of Hijrah. Allah said: "O you who believe, fasting has been prescribed upon you as it was prescribed upon those before you — that you may attain taqwa." (al-Baqarah 2:183). The wisdom is the cultivation of taqwa: when the believer leaves what is normally permissible (food, drink, marital relations) for the sake of Allah during the daylight hours, his soul is trained to leave what is forbidden in all hours. Fasting is also a private act of worship between the servant and his Lord — none can verify it but Allah — and so He attached its reward to Himself: "Every deed of the son of Adam is for him, except fasting — it is for Me, and I shall reward for it." ([al-Bukhari 1894](/hadith/bukhari/1894), Muslim 1151).