Ha'azinu: Chapter 40
The shining countenance of Zeir Anpin

We hear about the two colors of the face of Zeir Anpin, red and white. When sins multiply on earth, the face illuminates in red and judgments prevail. When people are righteous then the white shines from Atika Kadisha, and everything is illuminated with mercy. We hear that all the angels assume the colors that this face assumes.