The Lord be witness The Lord be a hearer; so the Hebrew word is. Whatever we speak, it concerns us to remember that God is a hearer! The people made him head, &c. They confirmed in full assembly, by unanimous consent, what the elders, who had been sent to him, had promised. Jephthah uttered all his words before the Lord That is, before the public congregation, where God was usually and then especially present. This most probably refers to the words of the people, in making him captain and head over them, which, it is likely, Jephthah repeated with an audible voice, calling God to witness to them at the same time, that the people might look upon their promise as more solemn, and that there might be no dispute afterward about the offer which they now made to him.
Related Commentaries of Judges 11:10
Judges 11:10-11
10 And the elders of Gilead said unto Jephthah, The LORD be witnessc between us, if we do not so according to thy words.
11 Then Jephthah went with the elders of Gilead, and the people made him head and captain over them: and Jephthah uttered all his words before the LORD in Mizpeh.