Ghudayf bin Harith reported,

I passed by Umar while he was with a group of his companions, and one of them caught up with me and said, "Young man, supplicate to Allah for good on my behalf, may Allah bless you."I said, "Who are you, may Allah have mercy on you?"He said, "I am Abu Dharr."I said, "May Allah forgive you. You are more deserving."He said, "I heard Umar say, 'What an excellent young man,' and I heard the Messenger of Allah ﷺ say, 'Allah has placed the truth upon the tongue of Umar, by which he speaks.'"

حدثنا يعلى بن عبيد حدثنا محمد يعني ابن إسحاق عن مكحول

عن غضيف بن الحارث قال

مررت بعمر ومعه نفر من أصحابه فأدركني رجل منهم فقال يا فتى ادع الله لي بخير بارك الله فيك قال قلت ومن أنت رحمك الله قال أنا أبو ذر قال قلت يغفر الله لك أنت أحق قال إني سمعت عمر يقول نعم الغلام وسمعت رسول الله ﷺ يقول إن الله عز وجل وضع الحق على لسان عمر يقول به