A: If a nonMuslim testifies that there is no deity but Allah and that Muhammad is the Messenger of Allah out of belief and Yaqin (certainty), and awareness of the meaning, and acts according to this, they have entered Islam. The person should then be asked to offer Salah (Prayer) and to fulfill the other rules of Islam. When the Prophet (peace be upon him) sent Mu'adh to Yemen, he (peace be upon him) said to him,
Invite them to testify that there is no god but Allah and that Muhammad is the Messenger of Allah. If they obey you in that, inform them that Allah has enjoined on them five prayers (to be offered) in every day and night.
If they obey you in that, inform them that Allah has enjoined on them Sadaqah (i.e. obligatory charity) to be taken from the rich among them and given to the poor among them. The Prophet (peace be upon him) ordered that they should be directed to perform Salah and give Zakah (obligatory charity) after they declare Tawhid (Oneness of Allah) and Iman (faith) in the Messenger (peace be upon him). If a nonMuslim does so, they take the ruling of Muslims. They should then be asked to offer Salah and observe the other religious principles. If they refrain from doing them, they will fall under other rulings, such as if they abandon Salah; the ruler must ask such a person to repent; otherwise, they will be subject to capital punishment. The same applies to the rest of the rulings of Islam, according to which they should be dealt with as they deserve.