Maliks Muwatta Book 20, Hadith Number 24.
Section : Where People Should Enter Ihram.
Abdullah ibn Umar said, “I heard these three from the Messenger of Allah, may Allah bless him and grant him peace. I was also told that the Messenger of Allah, may Allah bless him and grant him peace, said, ‘The people of Yemen should enter ihram at Yalamlam.'”