C. F. Keil and Franz Delitzsch on Judges 11:9

Jdg 11:9

Jephthah assented to this: “If ye will take me back to make war upon the Ammonites, and Jehovah shall give them up to me (lit. 'before me,' as in Jos 10:12; Deu 2:31, etc.), I will be your head.” “I” is emphatic as distinguished from he; and there is no necessity to regard the sentence as a question, with which the expression in Jdg 11:10, “according to thy words,” which presuppose an affirmative statement on the part of Jephthah, and not a question, would be altogether irreconcilable.