Ruk'u

Ruku is one section of the prayer or salat as it is performed by Muslims. A Muslim must perform 5 daily prayers as part of his/her faith. The entire method of the prayer consists of several parts, including standing erect with hands on the chest, bowing at the waist with the chest perpendicular to the ground and the hands on the knees, bowing down with the forehead and nose touching the ground, and sitting. The section of the prayer where the person bows at the waist is called ruku. Any part of the prayer which is intentioannly left outs cancels the prayer and makes it invalid. So, ruku must be performed in each prayer. Aside from the five daily prayers for Muslims, there are also a range of other optional prayers. However, all forms of these prayers are exactly the same as they contain the same sections, and so ruku is always a part of prayer. The number of times a person bows down and stands up again is the only things that will vary between the compulsory and the optional prayers.