Ala. Code § 12-21-221: Witness Having Pecuniary Interest in Case.

There shall be no exclusion of a witness in a criminal case because, on conviction of the defendant, he may be entitled to a reward or to a restoration of property or to the whole or any part of the fine or penalty inflicted. The witness may be examined touching such circumstances, but the examination goes to his credibility and not to his competency as a witness.