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.
أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ كَانَ لاَ يُخْرِجُ فِي زَكَاةِ الْفِطْرِ إِلاَّ التَّمْرَ إِلاَّ مَرَّةً وَاحِدَةً فَإِنَّهُ أَخْرَجَ شَعِيرًا