It is narrated from al-Sha'bi (may Allah have mercy on him) that Sayyiduna Umar (may Allah be pleased with him) said: "Kalalah is one who has no children." Sayyiduna Abu Bakr (may Allah be pleased with him) said: "Kalalah is one who has neither children nor parents." When Sayyiduna Umar (may Allah be pleased with him) was stabbed, he said: "I feel ashamed to differ with Sayyiduna Abu Bakr (may Allah be pleased with him); kalalah is one who has neither children nor parents."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الفرائض / 12273