Prayer is called "salat" in Arabic and means "supplication for good" in the dictionary. And in the Shari'ah it is a collection of words and actions that begin with takbir and end with salam. Prayer became fard on the night of Isra, before the Prophet's emigration peace be upon him.

It is repeatedly emphasized in the Qur'an, the Sunnah and the Ijma' that the five daily prayers are fard. Prayer is a fard ayn for every matured Muslim. It is fard for everybody to perform the prayer for himself. Whoever denies namaz, becomes a disbeliever (kafir) and backslides (to lapse morally or in the practice of religion) Islam. 

There is a difference of opinion regarding the one who recognizes the obligation of prayer but abandons it. Some categories say, "Anyone who leaves prayer even one time will be an unbeliever".

Jumhur ulamas say that such a person does not become an infidel and does not leave the scope of Islam, but he becomes a sinner and a fasiq, and will suffer the torments of both worlds. Everyone has agreed that the one who leaves the prayer will be punished in the Hereafter for every prayer he left. Also, all ulamas have agreed that there will be punishment in this world. But there are some disagreements about the type of punishment.