Section: The qafah (lineage experts) are a group of people who identify lineages through resemblance. This is not limited to a specific tribe; rather, whoever is known to possess knowledge of this and has a recurring record of accuracy is considered a qa'if. It is said that they are most numerous among the Banu Mudlij, the kin of Mujazziz al-Mudliji, who saw Usamah and his father Zayd when they had covered their heads while their feet remained exposed, and he said: "These feet are some from others." Iyas ibn Mu'awiyah al-Muzani was a qa'if, and it was likewise said regarding Shurayh. The statement of a qa'if is not accepted unless he is male, upright (adl), experienced in being accurate, and free (hurr); for his statement constitutes a legal judgment (hukm), and legal judgments require these conditions. Al-Qadi said: The expertise of a qa'if is established through testing. This is done by leaving the child with ten men other than the one claiming him, and showing him to the qa'if. If he attaches the child to one of them, his statement is rejected because we have verified his error. If he does not attach him to any of them, we show him to the qa'if with twenty men including the claimant; if he attaches him to the claimant, the lineage is established. Even if he is tested by seeing a child [of known lineage] with a group of people including his father or brother, and he attaches him to his relative, his accuracy is known; but if he attaches him to someone else, his statement is rejected, then it is permissible. This testing when presenting the child to the qa'if is for the sake of caution in verifying his accuracy. If we do not test him in the present instance, provided he is famous for his accuracy and soundness of knowledge on many occasions, it is permissible. We have narrated that a noble man doubted a child born to his slave-woman and refused to acknowledge him. Iyas ibn Mu'awiyah passed by him at a school while Iyas did not know him, and he said: "Call your father for me." The teacher said to him: "And who is this one's father?" He said: "So-and-so." He asked: "How did you know he is his father?" He replied: "He resembles him more than one crow resembles another." The teacher stood up, delighted, and went to the father to inform him of Iyas's statement. The man went out and asked Iyas, saying: "How did you know that this is my child?" He said: "Glory be to Allah! Could your child be hidden from anyone? He is indeed more similar to you than one crow is to another." The man was pleased and acknowledged his child.