"I heard the Messenger of Allah say: 'There is no one on earth, or under the sky, who speaks more truthfully than Abu Dharr.'" (Using translation from Ibn Mājah 156)
سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ مَا أَقَلَّتِ الْغَبْرَاءُ وَلَا أَظَلَّتِ الْخَضْرَاءُ مِنْ رَجُلٍ أَصْدَقَ مِنْ أَبِي ذَرٍّ