Sayyiduna Ma'qil bin Yasar (may Allah be pleased with him) said that Sayyiduna Umar (may Allah be pleased with him) asked the people: "Does anyone know anything from the Messenger of Allah (peace and blessings be upon him) concerning the grandfather?" Sayyiduna Ma'qil (may Allah be pleased with him) said: "He (peace and blessings be upon him) gave him a sixth." Sayyiduna Umar (may Allah be pleased with him) asked: "Along with whom, woe to you?" Sayyiduna Ma'qil (may Allah be pleased with him) said: "I do not know." Sayyiduna Umar (may Allah be pleased with him) said: "May you never know!"
In one narration, Amr bin Maymun (may Allah have mercy on him) said: I performed Hajj with Sayyiduna Umar (may Allah be pleased with him). Sayyiduna Umar (may Allah be pleased with him) called out to the people: "Has anyone heard anything from the Messenger of Allah (peace and blessings be upon him) concerning the grandfather?" Sayyiduna Ma'qil bin Yasar (may Allah be pleased with him) stood up and said: "I heard the Messenger of Allah (peace and blessings be upon him); an inheritance case in which there was a grandfather was brought to him, and he (peace and blessings be upon him) gave him a sixth or a third." Sayyiduna Umar (may Allah be pleased with him) asked: "What was the case?" Sayyiduna Ma'qil (may Allah be pleased with him) said: "I do not know." Sayyiduna Umar (may Allah be pleased with him) struck him (lightly) and said: "May you never know! What prevented you from knowing?"
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الفرائض / 12409