Sunan Ibn Majah, Chapter: The Book of the Sunnah

I was sitting with Abu Darda' in the mosque of Damascus, when a man came to him and said: 'O Abu Darda', I have come to you from Al-Madinah, the city of the Messenger of Allah (saw), for a Hadith which I have heard that you narrate from the Prophet (saw).' He said: 'Did you not come for trade?' He said: 'No.' He said: 'Did you not come for anything else?' He said: 'No.' He said: 'I heard the Messenger of Allah (saw) say: "Whoever follows a path in the pursuit of knowledge, Allah will make easy for him a path to Paradise. The angels lower their wings in approval of the seeker of knowledge, and everyone in the heavens and on earth prays for forgiveness for the seeker of knowledge, even the fish in the sea. The superiority of the scholar over the worshipper is like the superiority of the moon over all other heavenly bodies. The scholars are the heirs of the Prophets, for the Prophets did not leave behind Dinar of Dirham, rather they left behind knowledge, so whoever takes it has taken a great share.'" (Daif)