This is part 2 of 2 of “Zakat”, book 17 of Muwatta Malik — Hadith 628–629. The book is long enough that it is split across 2 pages so each one stays quick to load; the parts run in order and are linked at the foot of the page.
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ لاَ يُخْرِجُ فِي زَكَاةِ الْفِطْرِ إِلاَّ التَّمْرَ إِلاَّ مَرَّةً وَاحِدَةً فَإِنَّهُ أَخْرَجَ شَعِيرًا .
Yahya related to me from Malik from Nafi that Abdullah ibn Umar would always pay the zakat al-fitr in dates, except once, when he paid it in barley
حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ يَبْعَثُ بِزَكَاةِ الْفِطْرِ إِلَى الَّذِي تُجْمَعُ عِنْدَهُ قَبْلَ الْفِطْرِ بِيَوْمَيْنِ أَوْ ثَلاَثَةٍ .
Maliksaid, "Payment of all types of kaffara, of zakat al-fitr and of the zakat on grains for which a tenth or a twentieth is due, is made using the smaller mudd, which is the mudd of the Prophet, may Allah bless him and grant him peace, except in the case of dhihar divorce, when the kaffara is paid using the mudd of Hisham, which is the larger mudd." Yahya related to me from Malik from Nafi that Abdullah ibn Umar used to send the zakat al-fitr to the one with whom it was collected together two or three days before the day of breaking the fast
Text from the open hadith-api dataset. Hadith numbering follows that edition and can differ slightly from a printed copy — check the Arabic against a trusted mushaf of hadith before relying on a reference.