Sa'id bin al-Musayyab (may Allah have mercy on him) said that Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) made the grandmother of a man from Thaqif an heir in the presence of her son.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الفرائض / 12287