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. (Using translation from Abū Dāʾūd 2896)
أَنَّ رَجُلًا أَتَى النَّبِيَّ ﷺ فَقَالَ إِنَّ ابْنَ ابْنِي مَاتَ فَمَا لِي مِنْ مِيرَاثِهِ؟ فَقَالَ لَكَ السُّدُسُ فَلَمَّا وَلَّى دَعَاهُ فَقَالَ لَكَ سُدُسٌ آخَرُ فَلَمَّا وَلَّى دَعَاهُ فَقَالَ إِنَّ السُّدُسَ الْآخَرَ طُعْمَةٌ