Why was he wearing dirty garments?
Rashi citing Targum Yonasan: His sons married women Pasul for Kehunah.
Radak: This is a Mashal, for his sons married Nochriyos, like Targum Yonasan says. Chazal said (Sanhedrin 93a) that due to not protecting against his sons for this 1 , he was wearing dirty garments. Would Yehoshua wear dirty garments?! Rather, it is a Mashal for this ? "Asher Hoshivu Nashim Nochriyos mi'Bnei Yeshu'a" (Ezra 10:18).
Malbim: This hints to a second judgment against him ? is he proper to serve as Kohen Gadol, for his sons married Nochriyos? Because this judgment was about [whether he should wear] Bigdei Kehunah, The verse depicts that under the Bigdei Kehunah he wore clothes that indicate his sins. Also, this hints to what actually happened ? his garments were burned, for they were dirty [with sin], and not proper for a miracle.
Malbim: Ibn Ezra asked, the verse teaches that they married Nochriyos after Yehoshua died! This is not difficult. It means that they married Nochriyos a long time ago.
