False oaths are of three kinds:—
(1) Al-Yamīnu ʾl-G͟hamūs (اليمين الغموس). An oath taken concerning a thing already past, in which is conveyed an intentional falsehood on the part of the swearer: such an oath is highly sinful, the Prophet having declared—“Whosoever sweareth falsely, the same shall be condemned to hell.”
(2) Al-Yamīnu ʾl-munʿaqid (اليمين المنعقد). An oath taken concerning a matter which is to come. Thus, a man swears that he will do such a thing, or he will not do such a thing, and where he fails in this, expiation is incumbent upon him, which expiation is established on the authority of the sacred writings.
(3) Yamīnu ʾl-Lag͟hw (يمين اللغو). An oath taken concerning an incident or transaction already past, where the swearer believes that the matter to which he thus bears testimony accords with what he swears, though it should happen to be actually otherwise; in which case it may be hoped from the divine mercy that the swearer will not be condemned for such an oath.
The expiation, or kaffārah, is of no avail for the Yamīnu ʾl-G͟hamūs, but it is necessary for the Yamīnu ʾl-munʿaqid. It consists of either feeding or clothing ten poor persons, or releasing a Muslim captive.
The Muslim law with regard to oaths is a modification of the Talmudic law, for from the Divine law the Jewish doctors deduced many special cases of perjury, which are thus classified:—
(1) Jus jurandum promissorium, a rash or inconsiderate oath for the future, or a false assertion respecting the past ([Lev. v. 4]).
(2) Vanum, an absurd contradictory assertion.
(3) Depositi, breach of contract denied ([Lev. xix. 11]).
(4) Testimonii, judicial perjury ([Lev. v. 1]). (H. W. P. in Smith’s Dict. of the Bible.)