turning from good to objectionable and back again. Take the example of going bare-headed: its social value varies from place to place. Among people of honor in the eastern lands it is regarded as unbecoming, whereas in the western lands it is not considered improper at all. The legal ruling therefore changes in line with that variation.

Know, however, that the change of rulings in response to changing customs does not amount to any alteration of the original divine address. The Sharia has been laid down as something everlasting. What we mean by “change” is simply that, when customs diverge, each custom is referred back to its own underlying legal principle, and the judgment is issued accordingly.

The default principle: worship is pure devotion, while customs are judged by their underlying reasons

With respect to worship, the foundation is servitude—without probing into the rationale behind its particulars. Several considerations demonstrate this:

1. Inductive evidence: purification, for example, never extends beyond the body part for which it is prescribed; the prescribed prayers are confined to specific acts—if one departs from them, the act no longer counts as worship; a particular form of remembrance is required in one posture but not in another; and ritual ablution for minor impurity is restricted to pure water, even though physical cleanliness could be achieved by other means.
2. Human intellects have never independently discerned the logic that underlies devotional acts in the way they grasp the rationales of customary matters. On the contrary, in most cases the intellect has gone astray, which is why earlier revealed laws were altered over time. This shows that reason alone cannot grasp or define the purposes of worship, and so we are dependent on revelation in this sphere.

Because of this, Allah excused the people who lived in periods between messengers for not finding the guidance. He said, “We would never punish until We had sent a messenger” (17:15).

Once this is established, there is no recourse in matters of worship except to the limits set by the Lawgiver—that is the essence of devotion. Accordingly, the one who confines himself to simple imitation of the revealed prescriptions will be closer to the truth and more in line with the path of the righteous predecessors.