Judges 8:19

“And he said, they were my brethren, even the sons of my mother, etc.] His brethren by his mother’s side, but not by his father’s side; or the phrase the sons of my mother is added, to show that he did not mean brethren in a large sense, as all the Israelites were, but in a strict sense, being so nearly related as his mother’s children: as the Lord liveth, if ye had saved them alive, I would not slay you; for not being Canaanites, he was not obliged by the law of God to put them to death, and by the law of nations, as they had surrendered themselves, and were made prisoners of war, they ought to have been saved; but as they appeared to be murderers, and had slain the Israelites in cold blood,…”

“They were my brethren, even the sons of my mother--That is, uterine brothers; but, in all countries where polygamy prevails, "the son of my mother" implies a closeness of relationship and a warmth of affection never awakened by the looser term, "brother."”

“The sons of my mother - A much closer relation than that of brothers by the father only. (Compare Genesis 43:29; Deuteronomy 13:6; Psalms 69:8). This is the only hint preserved of the transaction. We cannot say exactly when the slaughter of Gideon’s brethren on Mount Tabor took place, whether before the outbreak of the war Judges 6:33, or in the retreat and flight of the Midianites Judges 7:22. return to 'Top of Page'”

“I would not slay - For being not Canaanites, he was not obliged to kill them; but they having killed his brethren, and that in cool blood, he was by law the avenger of their blood. Judges 8:20”