Hadith 506110
Chapter 17: Zakat - كتاب الزكاة
حَدَّثَنِي 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)."
Reference Muwatta Malik 506110
USC-MSA web (English) reference : Book 17, Hadith 34