Sahih Muslim
The Book Pertaining to Piety and Softening of Hearts (Kitab Al-Zuhd wa Al-Raqaiq)
Book Number: 042 / Hadith Number: 7074
This hadith has been narrated on the authority of Isma'il b. Khalid with the same chain of transmitters and the words are:" One amongst us would relieve himself as the goats do without anything mixing with its excrement."