Narrated Al-Miswar bin Makhrama and Marwan: The Prophet set out from Medina with over one thousand of his companions (at the time of the Treaty of Hudaibiya) and when they reached Dhul-Hulaifa, the Prophet garlanded his Hadi and marked it and assumed Ihram for'Umra.
— Sahih Bukhari, Volume 2, Book 26: Pilgrimmage (Hajj), Hadith #752