The prayer الصّلاة is from the most emphasized and stressed pillars of Islam, rather it is the second pillar after the testimonies of faith. It is the most emphasized actions of the limbs and the supporting structure of Islam. As it was narrated that the Prophet صلى الله عليه ويلم said:
“Its supporting structure is the prayer”
Meaning Islam. Indeed Allah obligated the prayer upon His prophet Muhammad صلى الله عليه وسلم in the highest of places that man has reached and during the best night to the messenger of Allah without any intermediary. Allah (initially) obligated it upon His Messenger to be prayed fifty times during the day and night, however He lighten this upon His servants until it became (only) five prayers to be perfromed and fifty by rewards. This shows the importance of the prayer and Allahs love for it and that it’s worthy for the people to dedicate much of their time to it. For this reason the Quran, sunnah and consensus of the muslims point to its obligation.
In the Quran, Allah says:
ۚ فَإِذَا اطْمَأْنَنتُمْ فَأَقِيمُوا الصَّلَاةَ ۚ إِنَّ الصَّلَاةَ كَانَتْ عَلَى الْمُؤْمِنِينَ كِتَابًا مَّوْقُوتًا
But when you become secure, re-establish [regular] prayer. Indeed, prayer has been decreed upon the believers at specified times. (an-Nisaa: 103)
The meaning of decreed is obligated. And the Prophet صلى الله عليه وسلم said to Mu’ādh bin Jabal when he sent him to Yemen:
“Teach them that Allah has obligated upon them five prayers every day and night“
And the muslims are upon a consensus regarding its obligation. For this reason the scholars said, if a person denies the obligation of the five prayers or even one of them, he is a disbeliever, who has apostated from Islam. His blood and wealth becomes lawful (under the authorities) except if he repents to Allah and (as long as) he is not new to Islam, while not knowing any of the legislations of Islam. This individual is excuse due to ignorance in this situation. He is then taught and if he persist after having knowledge of its obligation and rejecting its obligation then he is a disbeliever. Therefore the prayer is from the most obligated mandatory things in the religion of Islam.
Source: Fiqh al-Ibaadaat pg. 143-144
Translated by Abu Anas Atif Hasan