Why does the Torah forbid a woman to wear man's clothes and vice-versa?
Rashi and Targum Yonasan: So that she should not dress-up like a man and mingle with men (and vice-versa) for the sake of Z'nus (promiscuity) 1 .
See Torah Temimah, citing Nazir, 59a, and note 40. See also Ba'al ha'Turim.
What does the dual La'av incorporate?
Rashi #1: Refer to 22:5:2:1.
Rashi #2 and Targum Onkelos: It incorporates a prohibition against a man shaving his pubic or under-arm hair (like a woman). 1
Targum Yonasan: It incorporates a prohibition against a woman wearing a Talis and Tefilin, and against a man shaving his underarm or pubic hair, or to shave off his beard.
Da'as Zekenim (based on Targum Onkelos): It incorporates a prohibition against a woman girding weapons. 2
Shabbos, 94a: It incorporates a prohibition against a man removing white hairs from black hair or vice-versa. 3
Nazir, 59a: It incorporates a man wearing the colored clothes and the ornaments that women generally wear.
See Torah Temimah, note 44.
That explains why, in Shoftim 5:26, Ya'el killed Sisra with a tent-peg and a sledgehammer, and not with a sword or spear - as Targum Yonason explains there. See also Torah Temimah, note 41 and see Oznayim la'Torah, who explains how this is implied by the wording of the Torah.
See Torah Temimah, note 42. .
Why does the Torah forbid a woman to wear man's clothes and vice-versa?
Rashi and Targum Yonasan: So that she should not dress-up like a man and mingle with men (and vice-versa) for the sake of Z'nus (promiscuity) 1 .
Oznayim la'Torah: Because a man's role based on strength - is to defend his home and his country when necessary, whereas that of a woman is for beauty, and it is not befitting for them to switch roles. 2
What are the implications of "Ki To'avas Hashem ... "?
Rashi: It restricts the T orah prohibition to clothes that lead to abominable (promiscuous) behavior.