[Commentary]

This ḥadīth of ʿĀʾishah represents half of religious knowledge, for deeds are either inward or outward. The inward deeds are weighed against the ḥadīth of ʿUmar ibn al-Khattāb, may Allah be pleased with him, in which the Prophet ﷺ said, “Actions are only by intentions, and each person will have only what he intended.” The scale for outward deeds is this ḥadīth of ʿĀʾishah: “Whoever introduces into this affair of ours anything that is not part of it, it will be rejected”—meaning it is thrown back at its doer and not accepted from him.

The expression “this affair of ours” refers to our religion and our sacred law. Allah the Exalted says, “Thus We have revealed to you a spirit from Our command” (Q 42:52). Accordingly, the “command” of Allah in this ḥadīth is His legislation: whoever introduces into it something that does not belong to it will have it rejected. This is clear proof that any act of worship for which we do not know a basis in the religion of Allah is invalid.

From this we learn that knowledge is indispensable, because every act of worship contains conditions and pillars. At times, a strong preponderant assumption (ghalabat al-ẓann) may suffice in place of certain knowledge, as some texts indicate. For example, in the prayer: if you are unsure how many rakʿahs (units of prayer) you have performed and one number outweighs the other in your mind, proceed on the basis of what you deem more likely. Circumambulation (ṭawāf) of the Kaʿbah consists of seven circuits; if you are uncertain about the count, build on what you judge more probable. The same applies to purification: if you are reasonably sure that you have completed your wuḍūʾ (ablution) thoroughly, that is sufficient.

The essential point, then, is that knowledge—or, where the scriptural evidence shows it to be adequate, predominant assumption—is required; otherwise the act of worship is rejected. And once an act of worship is rejected, it becomes forbidden for a person to