What is the ruling when two men swear by divorce based on the identity of a flying bird (one swearing it is a crow, the other that it is a pigeon) and the bird flies away without identification?

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Neither man is judged to have committed divorce (hith). This is because the certainty of the marriage contract remains established, while the occurrence of divorce is doubtful. If a wife of one of them claims he divorced her, her statement is accepted because the presumption (al-asl) is in her favor, and certainty lies on her side.