Isaiah 8:2-3

8:2 Then I will summon ¹  as my reliable witnesses Uriah the priest and Zechariah son of Jeberekiah.” 8:3 I then had sexual relations with the prophetess; she conceived and gave birth to a son. The Lord told me, “Name him Maher-Shalal-Hash-Baz,

Malachi 2:14

2:14 Yet you ask, “Why?” The Lord is testifying against you on behalf of the wife you married when you were young, ²  to whom you have become unfaithful even though she is your companion and wife by law. ³ 

Hebrews 13:4

13:4 Marriage must be honored among all and the marriage bed kept undefiled, for God will judge sexually immoral people and adulterers.

[8:2]  ¹ tn The form in the text is a cohortative with prefixed vav (ו), suggesting that the Lord is announcing what he will do. Some prefer to change the verb to an imperative, “and summon as witnesses,” a reading that finds support from the Qumran scroll 1QIsa^a. Another option is to point the prefixed conjunction as a vav consecutive and translate, “So I summoned as witnesses.” In this case Isaiah is recalling his response to the Lord’s commission. In any case, the reference to witnesses suggests that the name and the child who bears it will function as signs.

[2:14]  ² tn Heb “the Lord is a witness between you and [between] the wife of your youth.”

[2:14]  ³ sn Though there is no explicit reference to marriage vows in the OT (but see Job 7:13; Prov 2:17; Ezek 16:8), the term law (Heb “covenant”) here asserts that such vows or agreements must have existed. References to divorce documents (e.g., Deut 24:1-3; Jer 3:8) also presuppose the existence of marriage documents.