Mu'awiya on Fire Temples
"You must not because they have made a treaty of friendship with us and those places of worship are theirs. The Persians say: 'We worship God and we have our firetemples and our sun. But it is not the sun and firetemple we worship; on the contrary they are ours in the same way that the [mihrabs and house of the Ka'aba] are yours.' Inasmuch as this is so, you should not [do this thing] since they have fire temples in the same fashion that Jews have synagogues and the Christians their churches. Since they are all [federates? This is a tricky word, but clearly refers to dhimma in its original sense of covenant of protection. Gold simply used "People of the Book" -bu], what difference does the place of worship make, since we worship God? If our prophet (The blessings of God be upon him!) had so desired he would have permitted none of these to exist, but would have exterminated all the infidels and all religions other than Islam. However, he did not do so, and did not destroy them, but made peace with them on the basis of [jizya]. This was the glorification of Islam since to the end of time, and as long as this world may exist, the Moslems can observe the truth of their own faith, and will constantly give thanks to Almighty God whenever they see and hear the defects of other religions."
This is striking because, unlike Jews and Christians, the Zoroastrians weren't supposed to be People of the Book, though they were usually treated as such.