Then: here the common conjunction is taken as a kind of temporal connector. But Revised English Bible leaves the conjunction untranslated, marking the passage of time by merely beginning a new paragraph at this point.
Gather: the utterance that begins with this plural imperative verb is elliptical, since it is not made clear to whom these words are addressed, yet the plural pronoun you is used at the end of the verse. Good News Translation resolves the problem by making the first part of the verse indirect discourse and then indicating clearly that it is all Israel that is addressed in the last part of the verse. Revised English Bible makes both parts of the verse into indirect discourse.
All Israel: again this refers to the totality of the people of Israel (see verses 2 and 3 above).
Mizpah is the name given to several different places in the Old Testament. The reference here is to the city located in the territory of Benjamin, about thirteen kilometers (or eight miles) north of Jerusalem. After the fall of Jerusalem in 587 or 586 B.C., Mizpah became the provincial capital of Judah (2 Kgs 25.23-25; Jer 40.7-12). The name Mizpah comes from a root meaning “to guard [or, to watch].” Nueva Biblia Española translates the name here and elsewhere as Atalaya, that is, “Watch-tower” in Spanish. Fox transliterates the Hebrew name, but follows it with the translation “Gather all Israel to Mitzpa/Lookout.”
I will pray … for you: though the Hebrew does not state explicitly in this verse that Samuel himself would go to Mizpah to pray for the people, the following verse suggests that he did. Translators may wish to state that Samuel will pray “there” for the people (so Good News Translation, Bible en français courant, Die Bibel im heutigen Deutsch).
Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on the First and Second Books of Samuel, Volume 1. (UBS Helps for Translators). New York: UBS, 2001. For this and other handbooks for translators see here .
