Salat is preceded by ritual ablution. Salat consists of the repetition of a unit called a rakʿah (pl. rakaʿāt) consisting of prescribed actions and words. The number of obligatory (fard) rakaʿāt varies from two to four according to the time of day or other circumstances (such as Friday congregational worship, which has two rakats). Prayer is obligatory for all Muslims except those who are prepubescent, menstruating, or are experiencing bleeding in the 40 days after childbirth.[1]