the ruler’s favor, by the sword, or by the life of any created being—I know of no disagreement among the scholars that such oaths are reprehensible and have been forbidden, and that swearing by them neither renders one an oath-breaker nor requires expiation. As to whether swearing by them is prohibited or merely discouraged, there are two positions within the school of Ahmad and elsewhere. The sounder position is that it is prohibited.

For this reason, our scholars—including al-Qādī Abū Ya‘lā and others—said that if a person declares, “The oaths of the Muslims shall be binding upon me if I do such-and-such,” he becomes liable for [what is required in the case of] an oath by Allah, a vow, divorce, manumission, and zihār. They did not mention prohibition, because an oath of prohibition is treated as zihār according to Ahmad and his companions. Since the legal consequence of both was the same in their view, they subsumed prohibition under zihār.

They did not, however, subsume a vow under an oath by Allah, even though an oath involving a vow may be discharged by expiation. This is because, upon breaking an oath involving a vow—known as a vow of obstinacy and anger—one may choose either to offer expiation or to fulfil the vow, whereas an oath by Allah entails expiation alone. Since their legal consequences differ, they classified them as two distinct oaths.

To be sure, according to the other report from Ahmad—namely, that an oath involving a vow entails expiation alone—the oath involving a vow is subsumed under an oath by Allah.

As for their disagreement, and that of other scholars, over whether a statement of this kind legally constitutes an oath, I shall discuss it, Allah Most High willing. My purpose here is only to enumerate the oaths sworn by Muslims.

As for oaths of allegiance, they said that al-Hajjāj ibn Yūsuf al-Thaqafī was the first to introduce them. The sunnah had been for people to pledge allegiance to the caliphs as the Companions pledged allegiance to the Prophet—peace and blessings be upon him—concluding the pledge just as they concluded contracts of sale, marriage, and the like,