Sahih Muslim
The Book on Salutations and Greetings (Kitab As-Salam)
Book Number: 026 / Hadith Number: 5464
'Uthman b. Abu al-'As reported that he came to Allah's Apostle (may peace be upon him) and he narrated like this. In the hadith transmitted on the authority of Salam b. Nuh there is no mention of three times,