Abu Nadra said, "One of our men called Jabir or Jubayr said, 'Iwent to 'Umar while he was Khalif to ask for something which I needed.I reached Madina during the night and went straight to him. I am someonewith intelligence and a ready tongue - or he said speech (meaning eloquence).I had looked at this world and thought little of it. I had abandoned itas not being worth anything. At 'Umar's side there was a man with whitehair and white clothes. When I had finished speaking, he said, "All thatyou have said is correct except for your attack on this world. Do you knowwhat this world is? This world is that in which we reach (or he said, 'whereour provision is') the Next World. It contains our actions for which wewill be rewarded in the Next World." He said, "A man who knows this worldbetter than I do worked in it." I asked, "Amir al-Mu'minin, who is thisman at our side?" He replied, 'The master of the Muslims, Ubayy ibn Ka'b.'"
English reference: Book 27, Hadith 476
Arabic reference: Book 1, Hadith 476