The Messenger of Allah ﷺ said, "The green sky has not shaded, nor has the dusty earth carried, any man more truthful in speech than Abu Dharr."
حدثنا يحيى بن حماد أخبرنا أبو عوانة عن الأعمش حدثنا عثمان بن قيس عن أبي حرب الديلي سمعت
قال رسول الله ﷺ ما أظلت الخضراء ولا أقلت الغبراء من رجل أصدق لهجة من أبي ذر
Its isnad is daif. Uthman bin Qays is Uthman bin Umayr, Abu Yaqzan, whose father's name is also given as Qays, as we explained at 6519, where Imam Ahmad narrated it there from Ibn Numayr from Amash. We have already discussed the hadith and pointed to this isnad there. It has also already appeared with this same isnad found here at 6630.