Sahih Bukhari
Companions of the Prophet
Volume: 005 / Book Number: 057 / Hadith Number: 36
Narrated Aslam:
Ibn 'Umar asked me about some matters concerning 'Umar. He said, "Since Allah's Apostle died. I have never seen anybody more serious, hard working and generous than 'Umar bin Al-Khattab (till the end of his life."