He heard their elders mention that a man from Quraysh had a share among the Banu Qurayzah, and he brought a dispute before the Messenger of Allah ﷺ concerning Mahzur, meaning the floodwater whose flow they divided among themselves. The Messenger of Allah ﷺ ruled between them that the water should reach up to the ankles, and that the upper landholder must not hold it back from the lower one.
أنه سمع كبراءهم يذكرون أن رجلا من قريش كان له سهم في بني قريظة، فخاصم إلى رسول الله ﷺ في مهزور- يعني السيل الذي يقتسمون ماءه. فقضى بينهم رسول الله ﷺ أن الماء إلى الكعبين، ولا يحبس الأعلى على الأسفل.
Abu Dawud (3638) narrated it from Muhammad bin Ala, who said, Abu Usama narrated to us, from Walid, meaning Ibn Kathir, from Abu Malik bin Thalaba, from his father Thalaba bin Malik, and he mentioned the hadith.Its chain is hasan because of Abu Malik bin Thalaba, who is Malik bin Thalaba bin Abu Malik Qurazi. Two narrators reported from him, and in Taqrib he is described as "acceptable," which is indeed the case, because he was corroborated by Muhammad bin Uqba bin Abu Malik Qurazi. Ibn Majah (2481) narrated it through this route, but the narrator from him, Zakariya bin Manzur bin Thalaba Qurazi, is daif.It is strengthened by what Malik narrated from Abdullah bin Abu Bakr bin Muhammad bin Amr bin Hazm, that it reached him that the Messenger of Allah ﷺ said, "Regarding the flood water of Mahzur and Muzaynib, it should be held back until it reaches the ankles, then the upper land releases it to the lower." He narrated it in the chapter on judgments (30).