Jephthah was illegitimate, and therefore not entitled under the LAW of MOSES to inherit his father’s property.Judges 11:1-2
11 Now Jephthah the Gileadite was a mighty man of valour, and he was the son of an harlot: and Gilead begat Jephthah.
2 And Gilead’s wife bare him sons; and his wife’s sons grew up, and they thrust out Jephthah, and said unto him, Thou shalt not inherit in our father’s house; for thou art the son of a strange woman.
Jephthah was the ninth Judge of Israel. He was born an illegitimate child, but judged over Israel for a period of six years (Judges 12:7). He is listed in the Book of Hebrews as one of the heroes of faith (Heb. 11:32). After his death, he was buried in a city of Gilead. Read Jephthah’s story in Judges, chapter 11, and chap. 12:1-7. The Heavenly Father used him in spite of his birth.
I am not sure how we can know these children are illegitimate. It requires deeper study.
https://www.kingjamesbibleonline.org/Illegitimate_Children/
Other Examples of illegitimate children:
Deuteronomy 23:2 “A bastard shall not enter into the congregation of the Lord; even to his tenth generation shall he not enter into the congregation of the Lord.”
Hebrews 12:8 “But if ye be without chastisement, whereof all are partakers, then are ye bastards, and not sons.”
Jephthah escapes the violence of his half-brothers; lives in the land of Tob
3 Then Jephthah fled from his brethren, and dwelt in the land of Tob: and there were gathered vain men to Jephthah, and went out with him.
Recalled from the land of Tob by the elders of Gilead
5 And it was so, that when the children of Ammon made war against Israel, the elders of Gilead went to fetch Jephthah out of the land of Tob:
Jephthah was made captain of the army and head of land of Gilead
5 And it was so, that when the children of Ammon made war against Israel, the elders of Gilead went to fetch Jephthah out of the land of Tob:
6 And they said unto Jephthah, Come, and be our captain, that we may fight with the children of Ammon.
7 And Jephthah said unto the elders of Gilead, Did not ye hate me, and expel me out of my father’s house? and why are ye come unto me now when ye are in distress?
8 And the elders of Gilead said unto Jephthah, Therefore we turn again to thee now, that thou mayest go with us, and fight against the children of Ammon, and be our head over all the inhabitants of Gilead.
Beth Johnson