"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)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ مَا أَظَلَّتِ الْخَضْرَاءُ وَلَا أَقَلَّتْ الْغَبْرَاءُ مِنْ ذِي لَهْجَةٍ أَصْدَقَ مِنْ أَبِي ذَرٍّ