וַֽיִּמְצְא֞וּ מִיּוֹשְׁבֵ֣י ׀ יָבֵ֣ישׁ גִּלְעָ֗ד אַרְבַּ֤ע מֵאוֹת֙ נַעֲרָ֣ה בְתוּלָ֔ה אֲשֶׁ֧ר לֹֽא־יָדְעָ֛ה אִ֖ישׁ לְמִשְׁכַּ֣ב זָכָ֑ר וַיָּבִ֨יאוּ אוֹתָ֤ם אֶל־הַֽמַּחֲנֶה֙ שִׁלֹ֔ה אֲשֶׁ֖ר בְּאֶ֥רֶץ כְּנָֽעַן׃ (ס)
E encontraram entre os habitantes de Yavesh-Gilad quatrocentas jovens virgens que não tinham conhecido homem algum no leito de homem, e trouxeram-nas ao acampamento em Shiloh, que está na terra de Kena'an.{פ}
Tze'enah Ure'enah
The four hundred virgins were brought to the city of Shilo and Israel sent [a message] to the remainder of the tribe of Benjamin who were in hiding. They said: come out and we will make peace with each other. The four hundred virgins from the city of Gilead were given to the tribe of Benjamin as wives. However, the four hundred virgins were not enough for them. The Israelites said: what should we do that the Benjaminites would take wives? We have sworn that we will not give our daughters to the Benjaminites. They thought of an idea. Every year there was a festival in the city of Shilo and the daughters of the city of Shilo used to dance in the fields. The Benjaminites should jump out from the vineyards to the dancers and each one should grab a maiden and run away with her, to take her as a wife. When the father of the maiden will complain to us, we will respond: they have been waiting to have wives and they ran to the dance and each one took a maiden that he liked as a wife.5Judges, 21:12–24.
Rabbeinu Bahya
You may well ask how the Israelites could determine which child fitted which criterion? We are told in Yevamot 60 that each child walked past the High Priest wearing his golden headband whereupon the faces of the girls who had had sexual experience turned green. This is the reason we were taught that a disease called דרקון is an indication that the afflicted person was an idolater. According to some, examination by walking by the ציץ was effective only for Gentiles, whereas Jewish girls would be seated on a wine casket if one wanted to determine their virginity. If a certain odour would be emitted this was considered proof that the girl in question was not a virgin. Rav Kahane derived the inadmissibility of the ציץ test for Jewish girls from Exodus 28,38 where the Torah describes the function of the golden headband as “it shall be on his forehead (High Priest) always, to bring them favour before Hashem.” The function of the ציץ did not include incriminating Jewish girls. Rav Ashi added that the word להם in that verse extends the beneficial function of said golden headband to Israelites only.