From Sahih Bukhari (Hadith 1715):
Narrated Anas bin Malik:The Prophet (ﷺ) offered four rak`at of Zuhr prayer at Medina and two rak`at of `Asr prayer at Dhul-Hulaifa. Narrated Aiyub: "A man said: Anas said, "Then he (the Prophet (ﷺ) passed the night there till dawn and then he offered the morning (Fajr) prayer, and mounted his Mount and when it arrived at Al-Baida' he assumed Ihram for both `Umra and Hajj
Reference: Bukhari 1715