Ezekiel 1:7

וְרַגְלֵיהֶם רֶגֶל יְשָׁרָה וְכַף רַגְלֵיהֶם כְּכַף רֶגֶל עֵגֶל וְנֹצְצִים כְּעֵין נְחֹשֶׁת קָלָל

Their legs were straight legs and the sole of their feet was like the sole of a calf's foot, and they sparkled like the color of burnished brass.

We previously discussed how, when saying kedusha in the repetition of the Amidah, we stand with our feet together to emulate the angels, based on this verse. But what about the part about the angels sparkling? Rashi explains that the angels shone in such a way that sparks appeared to fly off of them. He compares the word notzatzim (sparkling) to a similar usage in the Talmud (Yoma 37b), which describes the sun gleaming off the golden menorah of Queen Helena.