Exegesis:

kai gamēsē allēn ‘and he should marry another’: the meaning is, naturally, ‘another woman’ (not ‘another wife’).

gameō (cf. 6.17) ‘marry.’

moichatai ep’ autēn ‘he commits adultery with reference to her’: the great majority of commentators and translators understand autēn ‘her’ to refer to the first woman, whom the husband divorced (not the second, whom he married). Lagrange: “with regard to her: for it is with respect to her and to her rights that the second act is (an act of) adultery.” Translator’s New Testament and N. Turner, however, understands it to mean ‘commits adultery with her’ (i.e. the second woman); Turner appeals to Septuagint Jer. 5.8 chremetizō epi ‘neigh after’: he cannot, however, cite any instance of Mark’s using epi with the accusative meaning ‘with.’

epi ‘upon,’ ‘with reference to’: in a hostile sense, ‘against’ (cf. its use with this meaning in 3.24, 25, 26; 13.12; 14.48).

Translation:

The clause introduced by whoever may be shifted to a conditional clause, as is required by many languages, ‘if any one does…, he….’

Against her is not only a difficult expression for exegesis, but also a complicated phrase to translate. In some languages the reference must be made more specific, to be meaningful at all, e.g. ‘commits adultery against the first woman’ (Amganad Ifugao). In Huastec one may say ‘commits sin against her.’ In Conob an idiomatic phrase is commonly used ‘did evil against her eyes,’ but in some languages (e.g. Yaka, Tzeltal) the phrase is best omitted, since ‘adultery’ is understood with reference to the first woman, and any attempt to translate this phrase is either highly redundant or is understood as applying somehow to the second woman.

Quoted with permission from Bratcher, Robert G. and Nida, Eugene A. A Handbook on the Gospel of Mark. (UBS Handbook Series). New York: UBS, 1961. For this and other handbooks for translators see here .