Judges 11:34 says, And Jephthah came to Mizpeh unto his house, and, behold, his daughter came out to meet him with timbrels and with dances: and she was his only child; beside her he had neither son nor daughter.  When Jephthah returned home successfully, his daughter, his only child, was the first to come out of his door to meet him.  He had made a vow to God to sacrifice the first thing out of his door to God, as a burnt sacrifice.  This had been done basically as a bargaining tool, to help ensure God's giving Jephthah the victory.  We need to be careful what we promise to God as a bargaining tool.  If God does give us the victory over whatever problem we are facing, then we must be prepared to live up to our end of the bargain.  Verse thirty-five states,  And it came to pass, when he saw her, that he rent his clothes, and said, Alas, my daughter! thou hast brought me very low, and thou art one of them that trouble me: for I have opened my mouth unto the LORD, and I cannot go back.  His daughter was celebrating, but Jephthah said she had brought him low and was one of the ones who was causing him trouble because of his vow to God, which he couldn't take back.  We need to realize that when we make a vow to God that we cannot take it back without consequences, therefore we should know for sure what we are promising before we make the vow.  Verse thirty-six declares, And she said unto him, My father, if thou hast opened thy mouth unto the LORD, do to me according to that which hath proceeded out of thy mouth; forasmuch as the LORD hath taken vengeance for thee of thine enemies, even of the children of Ammon.  Jephthah's daughter told him that whatever he had vowed to the LORD concerning her to do it, because God had fulfilled His part by giving Jephthah victory over the Ammonites.  Though she wasn't sure what the vow was, she recognized the importance of fulfilling it.  We must also recognize the importance of fulfilling our vows to God, because He will always fulfill His part if we have truly made a vow to Him.  Verse thirty-seven adds, And she said unto her father, Let this thing be done for me: let me alone two months, that I may go up and down upon the mountains, and bewail my virginity, I and my fellows.  His daughter did ask for two months before the vow was fulfilled.  Verse thirty-eight declares, And he said, Go. And he sent her away for two months: and she went with her companions, and bewailed her virginity upon the mountains.  Jephthah allowed her to go with her companions for the two months.  I have to wonder what they both might have been thinking during this time.  Verse thirty-nine adds, And it came to pass at the end of two months, that she returned unto her father, who did with her according to his vow which he had vowed: and she knew no man. And it was a custom in Israel,  When she returned, Jephthah fulfilled his vow.  I cannot believe that this is something that God really wanted, but it was done because of the faithfulness of Jephthah to God.  I likewise believe that we may sometimes make vows to God that may not even be something that He would want us to do, but if we believe that God has given us success because of the vow, we cannot just suddenly change our mind about fulfilling our part of the vow.  That is why it is very important that we make sure that what we promise God is in accordance with His will.  Verse forty concludes, That the daughters of Israel went yearly to lament the daughter of Jephthah the Gileadite four days in a year.  The daughters of Israel went yearly to lament Jephthah's daughter for four days.  She had told Jephthah to fulfill his vow to God, and it had cost them both dearly.  We need to make sure that if we make a vow to God that it is not going to cost someone else even more than it costs us.