Thus, an unrestricted oath defaults to the legal sense and applies only to what is valid within that sense. Accordingly, whoever1 swears, “I will neither marry nor sell nor buy,” and then concludes an invalid contract does not break his oath. But if he restricts2 his oath to something whose validity is impossible—such as saying, “I will not sell wine,” and then sells it—he breaks his oath by that very act.

Section

When the legal definition is absent, oaths are governed by custom. Hence, whoever swears, “I will not have intercourse with my wife,” and then has relations with her has broken his oath; or says, “I will not set foot in So-and-so’s house,” and then enters it mounted or on foot, barefoot or shod, likewise breaks it; or says, “I will not enter a house,” and then goes into a mosque, a bathhouse, or a tent, he breaks it; or says, “I will not strike So-and-so,” and then throttles her, plucks out her hair, or bites her, he has broken his oath.

Where the legal definition is lacking, oaths are judged by custom. Thus, whoever swears, “I will not have intercourse with my wife,” and then consummates relations with her, or says, “I will not set foot in So-and-so’s house,” and then enters3 it mounted or on foot, barefoot or wearing shoes, has broken his oath; or4 says, “I will not enter a house,” and then enters a mosque, a bathhouse, or a tent, he has broken it; or5 says, “I will not strike So-and-so,” and then throttles her, plucks out her hair, or bites her, he has broken his oath.