In Islamic jurisprudence, the term is a noun phrase that denotes the "intention to fast during Dhu al-Hijjah." This intention (niyyah) is a mandatory spiritual prerequisite that must be established in the heart before commencing the voluntary fasts observed during the first nine days of Dhu al-Hijjah, the twelfth month of the Islamic lunar calendar. Without this conscious resolution to perform the act of worship for the sake of Allah, the physical act of abstaining from food and drink is not considered a valid fast in a religious context.
The concept of niyyah is foundational across all acts of Islamic worship, serving to distinguish a religious observance from a mundane habit. For these specific supererogatory fasts, the intention must be formulated before the dawn (Fajr) of the day of the fast. While it is not required to be verbally articulated, the internal resolve must be clear and specific to this particular act of worship. Jurisprudential discourse discusses whether a new intention is required for each day or if a single intention at the beginning of the period suffices for consecutive days of fasting. The most emphasized of these fasts is on the ninth day, the Day of `Arafah`, for those not performing the Hajj pilgrimage.
Practically, this means a Muslim resolves internally before dawn to undertake the fast of a specific day of Dhu al-Hijjah as a voluntary act of devotion. This mental act fundamentally transforms the fast from a mere physical discipline into a spiritually valid and rewardable deed. The validity and acceptance of the fast are therefore contingent upon the presence and sincerity of this preceding intention, highlighting the primacy of inner conviction over outward action in Islamic theology.
