in Aḥkām al-Dhimmah (1): “For it is the parents who turn a child into a Jew or a Christian; therefore, if they make him a Muslim, he becomes Muslim.”
The case in which both parents of the child—or one of them—die will be discussed under the chapter “The Ruling on the Apostate,” and it has also been mentioned earlier in the section on captives (2).
If someone embraces Islam on the condition that he will perform only two prayers, or that he will bow without prostrating—such as agreeing to make only a single prostration—his conversion is valid, yet he is still required to observe the prayer in its complete form, in accordance with the general texts.
It is advisable to issue them a written document specifying what has been collected from them, so that it may serve as proof whenever they need it.
One should also record the date of collection and the exact amount, lest anything be taken from them before a full year has elapsed; and the terms of the peace agreement reached with them should be entered in the administrative registers of the provinces, so that they can be held to it if they abandon, deny, or repudiate all or part of it.
Should a Christian become a Jew, or a Jew become a Christian, he is not left upon that change; nothing will be accepted from him except Islam or the religion he originally professed. Islam is the religion of truth, and his former faith is one for which covenant status has been granted. No other faith is accepted from him, for by adopting the new religion he acknowledges its falsehood, so he is not allowed to remain upon it—much like one who turns to Magianism.
If he refuses both Islam and his former religion, he is to be threatened, beaten, and imprisoned, but not executed, because he has not departed from the religions of the People of the Book; thus he is treated like anyone who remains on his own faith.
If Jews purchase a Christian slave and convert him to Judaism, they are disciplined, for they have committed a forbidden act. The slave does not become Muslim, for he has neither verbally pronounced nor, in legal effect, adopted the two testimonies of faith.