Al-Kalalah is one who has no child

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that he said: I was the last person to meet Sayyiduna Umar (may Allah be pleased with him), and I heard him say: "The view is what I said." I asked: What did you say? He said: "I said that kalalah is one who has no child."
This chain is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), and they did not record it.

It is narrated from Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) that he said: "There are three things which, had the Prophet (peace and blessings be upon him) fully explained them to us, would have been dearer to me than this world and everything in it: (first,) the caliphate, (second,) kalalah, and (third,) usury (riba)."
This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), and they did not record it.