Muwatta Imam Malik Book of Fara'id, Hadith 2
Yahya related to me from Malik from Ibn Shihab from Qabisa ibn Dhu'ayba that Umar ibn al-Khattab gave the grandfather "what people give him today."
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ قَبِيصَةَ بْنِ ذُؤَيْبٍ، أَنَّ عُمَرَ بْنَ الْخَطَّابِ، فَرَضَ لِلْجَدِّ الَّذِي يَفْرِضُ النَّاسُ لَهُ الْيَوْمَ .