Now therefore: this is the same transition expression as in verse 8. Here it introduces a kind of summary of David’s prayer. If the receptor language requires a logical connector in such a context as this, translators should choose whichever one is most natural. However, in some languages no explicit transition word will be required at this point.
May it please thee: this is a somewhat archaic but very polite way of asking for something. Translators should look for a form in their own language that is equally polite but natural. In English many versions use the rather stilted form “be pleased…” (New Jewish Publication Society’s Tanakh, New International Version, Revised English Bible). But others avoid the passive and say simply “Please…” (New Century Version) or use an imperative form without any introduction (New American Bible, Knox).
It may continue for ever: in some languages translators may prefer to say “I ask that you cause it to continue forever” or “I pray that it will endure always.”
Before thee: that is, in God’s presence. Probably David also had in mind that his descendants should continue in obedience to God, which is involved in the idea of remaining in his company.
For: a kind of logical marker in the thought of the writer. What follows is an explanation of the reason for what goes before. In effect David can ask God to bless him and his family because God has already said that he would do so. Some languages, however, do not require an explicit marker in such a context.
With thy blessing shall the house of thy servant be blessed: the passive form be blessed will have to be made active in many languages. Therefore this whole last clause may be rendered “you will continue to bless my family forever” or “you are the one who will always give blessing to those who follow in my family.”
Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on the First and Second Books of Samuel, Volume 2. (UBS Helps for Translators). New York: UBS, 2001. For this and other handbooks for translators see here .