William Horbury, "Old Testament Interpretation in the Writings of the Church Fathers," Mikra: Text, Translation, Reading and Interpretation of the Hebrew Bible in Ancient Judaism and Early Christianity, ed. Martin Jan Mulder (Peabody: Hendrickson, 2004) 745, 747.
The abiding prestige of OT law is illustrated when Tertullian, urging that Christians are bound to single marriages only, argues from 'the ancient documents of the legal scriptures' (in which he applies the priestly laws of Lev 20-21 to Christians)...
Fn: Tertullian, On Monogamy, 7-8, cf. his Exhortation to Chastity, 7 (based on an interpretative paraphrase of Lev 21:14...); contrast Clement of Alexandria, Strom. 3:82 (second marriage not forbidden by the law); it was a common view that second marriage (digamy) is best avoided (so for example Justin Martyr, 1 Apol. 15:5), and a series of canons forbid it to the clergy (cf. 1 Tim. 3:2, 12; Titus 1:6; and Leviticus 21:7, 13f. [priest not to marry widow or divorcee]).
Tertullian was a Christian thinker in the second-third centuries C.E.
The Tertullian texts Horbury cites are: On Monogamy 7.; Exhortation to Chastity 7.
For some reason, Tertullian believes there was an Old Testament law that forbade priests to "pluralize marriages," that is, to marry more than once. Horbury and others believe the passage he has in mind is Leviticus 21:14, which allows the high priest to marry only a virgin from his own people--not a divorcee, a widow, a prostitute, or a profane woman. But neither the Septuagint nor the Vulgate translates the passage as Tertullian interprets it.
In On Monogamy, Tertullian does refer to Leviticus 22:13, which says in the NRSV: "but if a priest's daughter is widowed or divorced, without offspring, and returns to her father's house, as in her youth, she may eat of her father's food." Tertullian interprets this to mean that a priest's daughter must return to her father's house if she is widowed or separated, meaning that she cannot remarry. As far as the "without offspring" part of the verse goes, Tertullian says that a widow or divorcee who has sons to take care of her doesn't need to return to her father.
Tertullian may assume a qal va-chomer here: if a priest's daughter cannot marry more than once, then how much more is it the case that a priest can't remarry, since he is holier?! For Leviticus 22:13, the Masoretic Text is simply presenting a hypothetical: "If a priest's daughter is widowed and divorced, and she has no child, and she returns to her father's house..." The Septuagint, however, says that "she will return," which implies more of a command. The Septuagint is more consistent with Tertullian's view.
Tertullian quotes Revelation 1:6, which calls Christians "priests." For that reason, he applies to all Christians certain priestly regulations in Leviticus 21. But he doesn't bind Christians to all of Leviticus' rules for priests. He denies, for example, that Leviticus 21's restrictions on priestly contact with corpses are for Christians, since Christ has rendered death irrelevant. For Tertullian, dead Christians are alive, in a manner of speaking.
While Tertullian holds fast to the "priesthood of all believers," other Christian writings apply Leviticus' priestly rules primarily to the clergy, as if those in an official office are the New Covenant priests. The Apostolic Canons 18-19 (fifth century) prohibit a husband of a widow, a divorcee, a harlot, a slave, two sisters, or a brother's daughter from serving as a clerk in holy orders. Apostolic Constitutions 6:17 (late fourth century) has the same rule, along with one that says a church official cannot be married more than once. It cites "the law" as an authority for its rules. The Apostolic Constitutions also appeals to Numbers 18:1-32 to justify offerings to the clergy. So Herbert Armstrong was not the first to equate church ministers with the Old Testament priesthood!
I find all of this interesting because it shows how early Christians approached the Old Testament law: they deemed it authoritative for Christians in some sense, but not in every detail. Also, Horbury has taught me another interpretation of I Timothy 3:2, 12 and Titus 1:6, which affirm that a church official must be the husband of one wife. Conservatives love to appeal to these passages to bar women and homosexuals from the clergy, but a strong trend in early Christianity was to see them as a prohibition for remarried people to serve as church officials. And there are conservative preachers who are remarried!