He heard their elders mention that a man from Quraysh had a share among Banu Qurayzah. He brought a dispute before the Messenger of Allah ﷺ concerning Mahzur, meaning the floodwater whose flow they shared 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.
حدثنا محمد بن العلاء حدثنا أبو أسامة عن الوليد يعني ابن كثير عن أبي مالك بن ثعلبة
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 لا يحبس الأعلى على الأسفل
[Hasan] Bayhaqi related it, 6/154, from the hadith of Abu Usama, with this same chain, and Ibn Majah also narrated it, no. 2481.Their nobles: I could not identify them, and the following hadith serves as a corroborating witness for it.