Al-Zuhri (may Allah have mercy on him) said: We do not know that anyone was made an heir in Islam except two grandmothers. This is also the view of Rabi'ah. Sayyiduna Sa'd (may Allah be pleased with him) said to Ibn Mas'ud (may Allah be pleased with him): "Are you the ones who make three grandmothers heirs?" as if Sa'd (may Allah be pleased with him) disapproved of it. In another narration the words are: "He made Hawwa' an heir from her sons."
Its chain is not strong.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الفرائض / 12346
Muhammad bin Nasr (may Allah have mercy on him) said: Reports have come from the Companions of the Prophet (peace and blessings be upon him) (may Allah be pleased with them) and a group of the Successors (may Allah have mercy on them) that they made three grandmothers heirs, along with the munqati' (broken-chain) hadith narrated from the Prophet (peace and blessings be upon him) that he made three grandmothers heirs. We do not know of anyone among the Companions of the Prophet (peace and blessings be upon him) who held otherwise, except what we have narrated from Sa'd (may Allah be pleased with him), whose chain the experts in hadith do not consider established.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الفرائض / 12347