‘Imrān ibn Husayn (may Allah be pleased with him) reported: A man came to the Prophet (may Allah's peace and blessings be upon him) and said: "My grandson died, so what do I inherit from him?" He said: "For you is a sixth." When the man turned to leave, the Prophet called him and said: "For you is another sixth." When he turned again to leave, he called him saying: "The other sixth is an extra share."
شرح الحديث :
A man asked the Prophet (may Allah's peace and blessings be upon him) about his share of inheritance in the estate of his grandson. He replied that the man is entitled to one sixth, and then when he turned to leave, he called him and told him that he is entitled to another sixth. The first is his prescribed share and the second is through agnation (Ta‘sīb). The scholars said that, in this case of inheritance, the deceased left two daughters and the man in question. The girls take two thirds and the man one third. The Prophet (may Allah's peace and blessings be upon him) gave him one sixth as a prescribed share because he is a grandfather of the deceased. He did not give him the other sixth simultaneously, so as not to think that his prescribed share is one third. He let him go and then called him to tell him that he is entitled to another sixth. As the man was leaving, the Prophet called him and told him that the other sixth is an extra share that he gets through agnation, after the prescribed shares are given out. What is given by agnation is not given on an obligatory basis, unlike the prescribed shares.