Sahih Muslim
The Book Pertaining to Piety and Softening of Hearts (Kitab Al-Zuhd wa Al-Raqaiq)
Book Number: 042 / Hadith Number: 7113
This hadith has been narrated on the authority of Wahb b. Kaisan with the same chain of transmitters but with this change that he said:" I earmark one-third for the poor, the needy and the wayfarers."