is substantial; and if they say, “This is slight,” then it is not substantial and does not affect the prayer.

Moreover, what counts as substantial differs according to the part that is exposed. If an area the size of a fingernail were exposed from the lower thigh, near the knee, and an area the size of a fingernail were exposed from the private parts themselves, the latter would be deemed substantial, whereas the former would not.

Thus, the ruling differs according to the location of what is exposed. On this basis, some people wear trousers, and when they prostrate, part of the lower back may become exposed, well above the buttocks. If the exposure is slight by customary standards—for example, no more than the width of a finger—then it is slight and does not matter. But if the trousers are short and, when he prostrates, a considerable amount becomes exposed, then this is substantial.

The apparent meaning of his statement, “Whoever has [part of his awrah] exposed,” is that this refers to exposure that occurs unintentionally. If he deliberately exposes it, the prayer is invalid, whether the exposure is slight or substantial, because there is a difference between becoming exposed and deliberately uncovering oneself. Accordingly, if a person deliberately uncovers any part of his awrah, even if only slightly and for a brief time, his prayer is invalid. For example, if he raises his trousers to scratch his knee, raising them until his thigh becomes visible—and we hold that the thigh is awrah—his prayer is invalid, because he deliberately uncovered it …

However, if the exposure is substantial but lasts only a brief time, such that it becomes exposed and then he covers it, the apparent meaning of the author’s words is that his prayer is invalid. This is not correct. Rather, we say: if a considerable amount becomes exposed and he covers it within a brief time, then his prayer