Exegesis:

to de kathisai ek dexiōn mou ē ex euōnumōn ‘but to sit at my right or at my left.’

euōnumos (15.27) literally ‘well-named’: an euphemism for ‘the left’ to avoid the sinister connotation of the word.

ouk estin emon dounai, all’ hois hētoimastai ‘is not mine to give, but (it is) for those for whom it has been prepared.’

all’ ‘but’ modifies the whole preceding phrase ‘to sit … is not mine to give,’ representing a denial on the part of Jesus that it is he who will decide who shall occupy the places of honor. The word is not to be translated ‘except’ as though Jesus were saying that he could not give the places of honor to the two brothers but only to those for whom these places had been prepared (as does Manson, following Turner: ‘I am not free to give to any but those for whom it is already destined’): on this interpretation cf. Swete.

hetoimazō (cf. 1.3) ‘prepare,’ ‘keep in readiness’: the passive ‘has been prepared’ presupposes God as the subject, ‘God has prepared.’ As Lagrange says, the word here reflects the concept of the predestinating action of God (which several translations convey by the use of ‘it is destined’: cf. Goodspeed, Moffatt, Manson; others, ‘it is reserved’: cf. The Modern Speech New Testament, Montgomery, Berkeley).

Translation:

Said may need to be rendered as ‘replied.’

We are able requires in certain languages expansion by some complementary verb, e.g. ‘we are able to do that.’

The clause to sit at my right hand … is not mine to grant must be recast in some languages, for one cannot use a possessive such as mine to describe a particular capacity to do something. For example, in Tzeltal one must change the clause to read ‘but I cannot give that you sit….’

It in the final clause (occurring twice) refers to the prerogative to sit on the right and the left. In some instances one must substitute a verb expression ‘to do that’ or a noun phrase ‘this position.’

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 .