New English Bible starts a new paragraph here, to mark the change of subject, though Remember links verses 2 and 3, at least in form. Remember may imply that the writer wants his readers to give practical help to those who are in prison. The tense of the verb suggests duration; Phillips has “Think constantly of.” As though rightly excludes the suggestion that the writer is writing directly to people in prison.

Remember those who are in prison may be more satisfactorily rendered as “Be concerned for those who are in prison” or “Be concerned for and give help to those who are in prison.”

Some languages do not have a convenient way of expressing a condition contrary to fact, such as as though you were in prison with them. An equivalent may be “think what it would be to be in prison with them” or “imagine yourself to be in prison with them.”

“In (the) body” (see Revised Standard Version) has been understood in various ways:
(1) “Members of the Christian fellowship,” understanding “body” in the figurative sense used by Paul (Jerusalem Bible “since you too are in the one body”), is most unlikely. There is no similar text in Hebrews; there is no definite article for “the” in the Greek, and this explanation does not fit in with verse 3a, which in other ways is parallel to 3b.
(2) Many translators think “in (the) body” means “in this mortal life” (compare 2 Cor 5.6 and Rom 7.24); Knox “since you are still in the world”; similarly Phillips.
(3) Other common language translations, and some other translations, suggest either:
(a) that the readers should identify themselves in sympathy with those who are ill-treated: Good News Translation as though you were suffering as they are (similarly Die Bibel im heutigen Deutsch); Translator’s New Testament “as if you too shared their lot”; or
(b) that the readers may suffer in the same way in the future: Bijbel in Gewone Taal “for the same can happen to you”; New American Bible “for you may yet suffer as they do.” This is not necessarily implied by the text, though it is perhaps included in (a), which also makes a good parallel with verse 3a, as though.

Barclay combines (2) and (3-a): “you have not yet left this life, and the same fate can happen to you.” This is not very likely. Where distinct meanings are involved, with no suggestion of deliberate ambiguity or play on words, the translator should choose the meaning which, after having considered all the possibilities, he thinks most likely. An alternative translation may, if necessary, be put in a footnote.

In accordance with the structure which is necessary in the rendering of verse 3a, one may translate verse 3b as “Be concerned for those who are suffering; consider what it is to suffer” or “… for you yourself to suffer.”

Quoted with permission from Ellingworth, Paul and Nida, Eugene A. A Handbook on The Letter of the Hebrews. (UBS Handbook Series). New York: UBS, 1983. For this and other handbooks for translators see here .