This is the Muslim whose Islam is complete. What is meant by “Muslim” here, however, is one who testifies that there is no god worthy of worship but Allah and that Muhammad is the Messenger of Allah. This is based on the Prophet’s statement to Mu'adh ibn Jabal: “You are going to a people from among the People of the Book, so call them to testify that there is no god worthy of worship but Allah and that I am the Messenger of Allah. If they obey you in this, then inform them that Allah has made five prayers obligatory upon them …” The hadith.
Thus, it is obligatory upon the one who testifies that there is no god worthy of worship but Allah and that Muhammad is the Messenger of Allah. It is not obligatory upon the disbeliever. What is meant by negating its obligation for the disbeliever is that he is not required to perform it while he remains a disbeliever, nor is he required to make it up after embracing Islam.
The proof that he is not required to perform it while in disbelief is the saying of Allah Most High:
“And nothing prevented their contributions from being accepted from them except that they disbelieved in Allah and His Messenger, and they do not come to prayer except lazily, nor do they spend except unwillingly.” [Quran 9:54]
This proves that the prayer is not accepted from him; and if it is not accepted from him, it is not valid. If it is not valid, it is not obligatory, for had it been obligatory and he performed what it required, it would have been valid.
Furthermore, the hadith of Mu'adh may also be cited as evidence, since it did not mention the obligation of prayer upon them until after the two testimonies.
Therefore, the disbeliever is not required to perform the prayer, nor is he required to make it up if he embraces Islam, due to the saying of Allah Most High: “Say to those who disbelieve: if they desist, they will be forgiven for what has already …”