The wolf is for the hyena, الذِّئْبُ لِلضَّبُعِ‏.‏

it is its horn. This proverb is used to describe a bad companion
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This proverb is used to describe the association of evil with its like, or the gathering of those similar in their wickedness. One of the closest English equivalents is:
“Birds of a feather flock together.”
Meaning: Birds of a feather flock together.
This is the most common and closest equivalent.
“Like attracts like.”
Meaning: A similar attracts its like.
“Two of a kind.”
Meaning: Two of the same ilk, often used to criticize or describe similar things.
“A rogue’s best companion is another rogue.”
Meaning: A rogue’s best companion is another rogue.
This is closest to the meaning of “two evil companions.”
And the closest to the spirit of the Arabic proverb is:
Birds of a feather flock together.”
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أي هو قرنه‏.‏ يضرب في قَرِيني سوء‏.‏