Surely the vow of Jephthah proceeded from the want of faith; else why did he doubt, why did he say if the Lord would deliver Ammon into his hands? And Reader! make an observation of it in your own experience whenever faith fails, the ill effects of it are near at hand. A little faith, or lively exercise, will carry a believer through great difficulties. But if the Lord for the trial of our grace, and to let us see what mere feathers we are in the wind of temptation, if the Lord for a moment withdraws the arm of his strength, by which our faith is upheld; depend upon it, in that moment we fall. Hence our dear Lord, in the exercise of his mercy when upon earth, so much praised the evidences of faith in his people, as if he seemed to suspend these mercies on this very principle. Believest thou that I am able to do this? According to your faith, so be it done unto you. Matthew 9:28-29.
Related Commentaries of Judges 11:30
Judges 11:30-31
30 And Jephthah vowed a vow unto the LORD, and said, If thou shalt without fail deliver the children of Ammon into mine hands,
31 Then it shall be, that whatsoeverd cometh forth of the doors of my house to meet me, when I return in peace from the children of Ammon, shall surely be the LORD'S, and I will offer it up for a burnt offering.