Narrated Imran ibn Husayn:

A man came to the Prophet ﷺ and said: My son has died; what do I receive from his estate? He replied: You receive a sixth. When he turned away he called him and said: You receive another sixth. When he turned away, he called him and said: The other sixth is an allowance (beyond what is due).

Qatadah said: They (the Companions) did not know the heirs with whom he was given (a sixth). Qatadah said: The minimum share given to the grandfather was a sixth.

حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ، أَخْبَرَنَا هَمَّامٌ، عَنْ قَتَادَةَ، عَنِ الْحَسَنِ، عَنْ عِمْرَانَ بْنِ حُصَيْنٍ، أَنَّ رَجُلاً، أَتَى النَّبِيَّ ﷺ فَقَالَ إِنَّ ابْنَ ابْنِي مَاتَ فَمَا لِي مِنْ مِيرَاثِهِ فَقَالَ " لَكَ السُّدُسُ " . فَلَمَّا أَدْبَرَ دَعَاهُ فَقَالَ " لَكَ سُدُسٌ آخَرُ " . فَلَمَّا أَدْبَرَ دَعَاهُ فَقَالَ " إِنَّ السُّدُسَ الآخَرَ طُعْمَةٌ " . قَالَ قَتَادَةُ فَلاَ يَدْرُونَ مَعَ أَىِّ شَىْءٍ وَرَّثَهُ . قَالَ قَتَادَةُ أَقَلُّ شَىْءٍ وَرِثَ الْجَدُّ السُّدُسَ .