Jamieson, Fausset and Brown on Hebrews 13:4

4. is, &c.--Translate, "Let marriage be treated as honorable": as He 13:5 also is an exhortation.

in all--"in the case of all men": "among all." "To avoid fornication let EVERY MAN have his own wife" (1Co 7:2). Judaism and Gnosticism combined were soon about to throw discredit on marriage. The venerable Paphnutius, in the Council of Nice, quoted this verse for the justification of the married state. If one does not himself marry, he should not prevent others from doing so. Others, especially Romanists, translate, "in all things," as in He 13:18. But the warning being against lasciviousness, the contrast to "whoremongers and adulterers" in the parallel clause, requires the "in all" in this clause to refer to persons.

the bed undefiled--Translate, as Greek requires "undefiled" to be a predicate, not an epithet, "And let the bed be undefiled."

God will judge--Most whoremongers escape the notice of human tribunals; but God takes particular cognizance of those whom man does not punish. Gay immoralities will then be regarded in a very different light from what they are now.