Musannaf Ibn Abi Shayba 33:441

Abu Khalid al-Ahmar narrated to us, from Muhammad ibn Ishaq, who said: My uncle Musa ibn Yasar narrated to me that Salman wrote to Abu al-Darda: "Indeed, in the shade of the Throne is a just leader; and a person of wealth who gave charity, hiding his right hand from his left; and a man whom a woman of status and lineage invited to herself, and he said: 'I fear Allah, the Lord of the worlds'; and a man who grew up, and his companionship, his youth, and his strength were in what Allah loves and is pleased with of deeds; and a man whose heart was attached to the mosques out of love for them; and a man who remembered Allah, and his eyes overflowed with tears out of fear of Allah; and two men who met, and one of them said to his companion: 'I truly love you for the sake of Allah.'" And he wrote to him: "Knowledge is like springs; Allah benefits with it whom He wills. An example of wisdom that is not spoken is like a body that has no soul. An example of knowledge that is not acted upon is like a treasure from which nothing is spent. And an example of the scholar is like a man for whom a lamp was lit on a path, so people began to seek light from it, and everyone prays for good for him."