From where did the Prophet (peace and blessings of Allaah be upon him) enter ihraam?

The Prophet (peace
and blessings of Allaah be upon him) entered ihraam from Dhu’l-Hulayfah
(which is now called Abyaar ‘Ali), i.e., he entered ihraam for Hajj and
‘Umrah and started to recite the Talbiyah from there, not from Madeenah.
That is because the Prophet (peace and blessings of Allaah be upon him)
defined the meeqaats for the rituals of Hajj and ‘Umrah, and he stated that
Dhu’l-Hulayfah was the meeqaat for the people of Madeenah. The Prophet
(peace and blessings of Allaah be upon him) would not command something then
go against it. It was narrated that Ibn ‘Abbaas (may Allaah be pleased with
him) said: “The Messenger of Allaah (peace and blessings of Allaah be upon
him) defined the meeqaat of the people of Madeenah as Dhu’l-Hulayfah; that
of the people of Shaam (Syria) as al-Jahfah; that of the people of Najd as
Qarn al-Manaazil; and that of the people of Yemen as Yalamlam. And he said:
“And these meeqaats are for the people at those very places, and besides
them for those who come thorough those places with the intention of
performing Hajj and ‘Umrah; and whoever is living within these boundaries
can enter Ihram from the place he starts, and the people of Makkah can start
from Makkah.” Narrated by al-Bukhaari (1524) and Muslim (1181).  

And it was narrated from Saalim ibn ‘Abd-Allaah ibn ‘Umar
(may Allaah be pleased with them) that he heard his father say: “The
Messenger of Allaah (peace and blessings of Allaah be upon him) never
entered ihraam except from the mosque” – meaning the mosque of
Dhu’l-Hulayfah, Narrated by al-Bukhaari (1541), Muslim )1186). And he did
ghusl in Dhu’l-Hulayfah too, because it was narrated from Khaarijah ibn Zayd
that his father saw the Prophet (peace and blessings of Allaah be upon
him) changing his clothes and doing ghusl. Narrated and classed as hasan by
al-Tirmidhi (classed as saheeh by al-Albaani in al-Mishkaat, 2547). 

And Allaah is the Source of strength.