Bulugh al-Maram, Book 4, Hadith 601 (In-Book)

'Amro bin Shu'aib narrated on the authority of his father, who reported on the authority of his grandfather (RAA) that the Messenger of Allah said: “The Zakah of the Muslims should be collected by their water trough.” Related by Ahmad.

وَعَنْ عَمْرِو بْنِ شُعَيْبٍ, عَنْ أَبِيهِ, عَنْ جَدِّهِ قَالَ: قَالَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-{ تُؤْخَذُ صَدَقَاتُ اَلْمُسْلِمِينَ عَلَى مِيَاهِهِمْ } رَوَاهُ أَحْمَد ُ 1‏.‏ ‏1 ‏- حسن.‏ رواه أحمد ( 6730 )‏.‏

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also referenced under: Book 4, Hadith 626 (English)