Muwatta Malik 608
موطأ مالك#608Sahihحَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنِ الثِّقَةِ، عِنْدَهُ عَنْ سُلَيْمَانَ بْنِ يَسَارٍ، وَعَنْ بُسْرِ بْنِ سَعِيدٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " فِيمَا سَقَتِ السَّمَاءُ وَالْعُيُونُ وَالْبَعْلِ الْعُشْرُ وَفِيمَا سُقِيَ بِالنَّضْحِ نِصْفُ الْعُشْرِ " .
Yahya related to me from Malik from a reliable source from Sulayman ibn Yasar and from Busr ibn Said that the Messenger of Allah, may Allah bless him and grant him peace, said, "On land that is watered by rain or springs or any natural means there is (zakat to pay of) a tenth. On irrigated land there is (zakat of) a twentieth (to pay)
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 17:31