The Messenger of Allah (may peace and blessings of Allah swt be upon him) said to Ali ibn Abi Taalib (may Allah swt please with him):

"By Allah, if a single person is guided by Allah through you, it will be better for you than a whole lot of red camels."

Related by Bukhari and Muslim. Riyad-us-Saliheen (Hadith # 1379)