Ata' (may Allah have mercy on him) related that Sayyiduna Abu Bakr (may Allah be pleased with him) used to say: "The grandfather is like the father when there is no father, just as the son's son is like the son when there is no son."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الفرائض / 12281