Exegesis:

anathematizein (only here in Mark) ‘to invoke anathema,’ ‘to devote to destruction,’ ‘to put under the curse’: the verb means to pronounce anathema (Hebrew cherem), i.e. ‘devoted to destruction,’ upon someone, in this case on the speaker himself. ‘May I be accursed if (what I say is not true)!’ For instances of this cf. 1 Sam. 20.13; 2 Sam. 3.9; Acts 23.12.

omnunai (cf. 6.23) ‘to swear,’ ‘to put oneself on oath’: neither one of the two verbs here employed would suggest vulgarity or profanity on the part of Peter (cf. Gould); they are rather, on his part, expressive and solemn protestations of the truth of his assertion.

Translation:

In most societies there is some means whereby a person may put himself under a curse if his statement is not true, e.g. ‘said that he wanted God to punish him if it were not so’ (Central Pame). However, in some languages the description of such a process would take a paragraph, since curses are not normally invoked as proof of one’s veracity. In these instances, ‘declare with solemn words’ or ‘say with very strong words’ may be the closest parallel.

Curse and swear are distinct processes, even though the witness of God or supernatural sanctions are invoked in both instances. In the first case, God is asked to punish one for not telling the truth, and in the second, God is asked to be a witness of the truth, e.g. ‘God truly sees me that I don’t know the one you say’ (Tzeltal).

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 .