Muwatta Malik #1886

Yahya related to me from Malik from Ishaq ibn Abdullah ibn Abi Talha that Anas ibn Malik heard Umar ibn al-Khattab return the greeting of a man who greeted him. Then Umar asked the man, "How are you?" He said, "I praise Allah to you." (Ahmadu ilayka Allah) Umar said, "That is what I wanted from you."