Musannaf Ibn Abi Shaybah 38533 — the first to do a thing, and who did

Abd al-Rahman bin Ghanm said that the first grandfather to inherit in Islam was Sayyiduna Umar bin al-Khattab (may Allah be pleased with him). He wanted to take all of the wealth, so I said to him: "O Commander of the Believers, they are a tree below you," meaning his grandsons.