From Sahih Bukhari (Hadith 4158):
Narrated Marwan and Al-Miswar bin Makhrama:The Prophet (ﷺ) went out in the company of 1300 to 1500 of his companions in the year of Al-Hudaibiya, and when they reached Dhul-Hulaifa, he garlanded and marked his Hadi and assumed the state of Ihram
Reference: Bukhari 4158