From Sahih Muslim (Hadith 2805):
Ibn 'Umar (Allah be pleased with them) reported that the Messenger of Allah (ﷺ) said:The people of Medina should enter upon the state of Ihram at Dhu'l-Hulaifa, and people of Syria at Juhfa, and people of Najd at Qarn (al-Manazil), and 'Abdullah (further) said: It has reached me that the Messenger of Allah (ﷺ) also caid: The people of Yemen should enter upon the state of Ihram at Yalamlam
Reference: Muslim 2805