Sahih Muslim
The Book on Salutations and Greetings (Kitab As-Salam)
Book Number: 026 / Hadith Number: 5552
Nafi' reported that Abu Lubaba happened to pass by Ibn 'Umar who lived in the fortified place near the house of 'Umar b. Khattab and was busy in keeping his eyes upon a snake and killing it, the rest of the hadith is the same.