From Sahih Bukhari (Hadith 3687):
Narrated Aslam:Ibn `Umar asked me about some matters concerning `Umar. He said, "Since Allah's Messenger (ﷺ) died. I have never seen anybody more serious, hard working and generous than `Umar bin Al-Khattab (till the end of his life)
Reference: Bukhari 3687