Musnad Ahmad 937:7

Yunus and ‘Affan narrated to us—the meaning is the same—they said: Hammad ibn Salamah narrated to us, from Burd Abu al-‘Ala’. ‘Affan said: He said: Burd Abu al-‘Ala’ informed us, from ‘Ubadah ibn Nusayy, from Ghudayf ibn al-Harith, that he passed by ‘Umar ibn al-Khattab, and he said: "What an excellent youth is Ghudayf." Then Abu Dharr met him and said: "O my brother, ask forgiveness for me." He said: "You are a companion of the Messenger of Allah, may Allah bless him and grant him peace, and you are more entitled to ask forgiveness for me." He said: "I heard ‘Umar ibn al-Khattab say: 'What an excellent youth is Ghudayf,' and the Messenger of Allah, may Allah bless him and grant him peace, has said: 'Indeed, Allah has placed the truth upon the tongue of ‘Umar and his heart.'" ‘Affan said: "Upon the tongue of ‘Umar, he speaks by it."