Poem #225 in the Kangin shū:

Karasu dani/ uki yo itoite/ sumizome ni/ sometaru ya/ mi o sumizome ni/ sometari
Has even the crow/ despising the world/ stained itself an inky black?/ stained its body/ inky black?

Ikeno Kenji 池野健二, editor of Iwanami's 1989 edition of this work, points out that many other poems from around this period compare the plumage of the crow to the traditionally black robes of the Buddhist priest, and that the crow as Buddhist imagery was not unheard of in other contexts.

For example, Nichiren's 1272 "Sado Letter" (佐渡御書) mentions casually that the crow is stained black by its past karma (烏の黒きも [...] も先業のつよくそみけるなるべし), and Nichiren in turn was quoting the Śūraṅgama Sūtra, in which the Buddha uses his knowledge of the reasons for the crow's blackness as an example of his omniscience of causes and conditions. ("阿難。我說佛法從因緣生。非取世間和合麤相。如來發明世出世法。知其本因隨所緣出。如是乃至恒沙界外一滴之雨。亦知頭數。現前種種松直棘曲鵠白烏玄。皆了元由。")

This is the point at which I should offer up some parallel examples from Western culture likening crows to priests, but unfortunately the only one that comes to mind is the second verse of "All This Time" by Sting.