The foremost task of translating is to translate what is there. What do the words say? What does the syntax mean? A translation might need to be more dynamic than literal to make the clearest sense in the target language, but it is still trying to translate what's there.
When should we “translate” what isn't there? And how do we do it?
There are at least three occasions for a translation to treat what isn't there: when the words that are there are abbreviated, when the words that are there were miscopied, and when non-verbal components are part of the communication.
This post considers abbreviated sayings. An example of an abbreviated saying in English would be the words: “So help me, if you do that again!” That first part, “so help me” is sometimes “God help me” and means something like, “I would need divine intervention to keep from doing X [something extreme].” In this case the request for “help” is a request to be restrained from doing something. Sort of. Sometimes at least, the speaker is asserting, “I will do this [right or wrong] unless God stops me” because it is primarily a threat, and not a request for help or hindrance.
Leaving the English example aside, let’s turn to Hebrew. The Hebrew word אִם (’im; “if [only]”) can begin an oath formula (see HALOT 60 and GKC 151e, 159dd, 167a). A full reporting of the oath would include both the request made of God and the promise made to God. Jacob and Jephthah provide examples of the full formula. In Gen 28:20-21 Jacob vows, “If (אִם) God is with me and protects me on this journey I am taking and gives me food to eat ... then the Lord will become my God.” Jephthah’s vow appears in Judges 11:30-31 “If (אִם) you really do hand the Ammonites over to me, then whatever is the first to come through the doors of my house to meet me...I will offer up as a burnt sacrifice.” See Num 21:2; 1 Sam 1:11; 2 Sam 15:8; and Ps 81:9-14 for other examples.
In 1 Chronicles 4 we hear only the first part of a vow. Jabez says, “If only (אִם) you would greatly bless me and expand my territory! May your hand be with me! [And another phrase for a future post].” Jabez’ promise is not recorded, only that God granted his request. By implication Jabez was faithful to his vow, so that his destiny was different than the expectation arising from the meaning of his name. (Jabez’ name sounds like the Hebrew word for pain and was given because of the extent of his mother’s birth pains.)
Perhaps Jabez’ vow in return had not been preserved by tradition, so the author could not include it. Or perhaps those details were simply less important to the purpose of the book. The original audience would recognize the formula and understand that a vow and faithfulness to it were implied. Likely the author wants to emphasize to the post-exilic community (the original audience of the Chronicles) that God answers prayer. Prayers appear in Chronicles at 1 Chr 5:20-22; 2 Chr 7:12-15; 20:6-12; 30:13-20; 32:24-26; 33:10-13. The emphasis in the book (1 and 2 Chr were originally one book) is quite arguably on God’s response and the people’s faithfulness.
So was the prayer of Jabez a prayer? Yes and no. If by prayer we mean broadly communication directed to God, yes. But more technically it was not a simple petition but a vow. If we consider and translate “the prayer of Jabez” to only be a prayer, then we miss not only his promise, but also his faithfulness to it. Like the original audience we should be encouraged that God really does answer prayer. And we should be challenged to consider our own faithfulness and our motivations in making requests. We certainly shouldn’t turn these verses into an example of what we can get for ourselves.
Back to the translation question. It is important to translate that first word (אִם; ’im) as “if only” (most translations render it “oh that you would” or “please [do X]”). Although “if only” may sound a bit awkward, that is the tip off that something else is expected-Jabez’ vow in return. Of course, we can’t insert the particular vow into the translation; we can’t add what isn’t there. But we can translate to signal there was something else. And for the something else, what could be more appropriate than the NET notes? And furthermore, it is good to know that in response to a comment that was left, the NET notes will be expanded in a future edition to provide a fuller explanation.