Muwatta Imam Malik Book of Zakat, Hadith 47

Yahya related to me from Ibn Shihab from Salim ibn Abdullah from his father that Umar ibn al-Khattab used to take a twentieth from the cereals and olive oil of the Nabatean christians, intending by that to increase the cargo to Madina. He would take a tenth from pulses.

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ سَالِمِ بْنِ عَبْدِ اللَّهِ، عَنْ أَبِيهِ، أَنَّ عُمَرَ بْنَ الْخَطَّابِ، كَانَ يَأْخُذُ مِنَ النَّبَطِ مِنَ الْحِنْطَةِ وَالزَّيْتِ نِصْفَ الْعُشْرِ يُرِيدُ بِذَلِكَ أَنْ يَكْثُرَ الْحَمْلُ إِلَى الْمَدِينَةِ وَيَأْخُذُ مِنَ الْقُطْنِيَّةِ الْعُشْرَ .