Sunan An-Nasa'i
Hadith #2921
It was narrated that Ibn Abbas said:""The Messenger of Allab passed by a man who was leading another man with something that he had stipulated in a vow. The Prophet took it and broke it, and he said: 'It is a vow.'"" (Sahih) Chatper 136. It Is Permissible To Speak During Tawaf