Sayyiduna Ghudayf bin al-Harith (may Allah be pleased with him) narrates from Sayyiduna Bilal (may Allah be pleased with him); Bilal (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Indeed, Allah, the Mighty and Majestic, has placed the truth upon the tongue and heart of Umar."
Hadith Referenceالمعجم الكبير للطبراني / باب الباء / 1073