He passed his miqaat and did not enter ihram from there, then he entered ihram from the miqaat of Madinah

Praise
be to Allah.

Firstly:

There is some scholarly discussion about
the miqaat of the people of Sudan; this has been mentioned in the answer to
question no. 41978. 

Secondly: 

If the people of Sudan come to Jeddah and
their miqaat was al-Juhfah, or in line with Yalamlam, or Jeddah itself –
according to the details discussed in the question referred to above –  but
they do not enter ihram from their miqaat, then they go to Madinah and they
enter ihram from Abyar ‘Ali, their ihram is valid. That is because it is
permissible for the one who passes by two miqaats to delay entering ihram
until he reaches the second miqaat, according to the more correct scholarly
opinion; this is also the view of the Hanafis. 

It says in Kanz ad-Daqaa’iq: If a
person from Madinah does not enter ihram from Dhu’l-Hulayfah [Abyar ‘Ali],
and he enters ihram from al-Juhfah, there is nothing wrong with that. The
same applies to anyone who passes by it who is not one of its people. 

It was narrated from Abu Haneefah that
(the one who does this) must offer a compensatory sacrifice, and that
applies the closer the second miqaat is to Makkah. 

However, the first view is more correct.
When ‘Aa’ishah (may Allah be pleased with her) wanted to do Hajj, she
entered ihram from Dhu’l-Hulayfah, and when she wanted to do ‘umrah she
entered ihram from al-Juhfah. It is as if she wanted to increase the reward
in Hajj because it is of greater virtue. If al-Juhfah had not been a miqaat
for her, it would not have been permissible for her to delay entering ihram
for ‘umrah, because there is no difference between Hajj and ‘umrah with
regard to the miqaat for those who are coming from beyond the miqaat
boundaries.

End quote from Tabyeen al-Haqaa’iq
Sharh Kanz ad-Daqaa’iq (2/7) 

The scholars of the Standing Committee
(11/155) were asked:

A pilgrim intends to do Hajj but he had
business to attend to in Makkah, then in Madinah. He passed the miqaat
without entering ihram, and entered Makkah, then he went to Madinah, and
entered ihram from the miqaat of Madinah for Hajj. What is the ruling on his
actions? 

They replied: 

So long as the pilgrim went out to the
miqaat of the people of Madinah and entered ihram, there is nothing wrong
with him having entered Makkah without entering ihram, although it would
have been better for him to enter ihram from the first miqaat. End quote. 

Standing Committee for Academic Research
and Issuing Fatwas 

‘Abdullah ibn Ghadyaan, ‘Abd ar-Razzaaq
‘Afeefi, ‘Abd al-‘Azeez ibn ‘Abdullah ibn Baaz 

Shaykh Ibn ‘Uthaymeen (may Allah have
mercy on him) was asked: A man came from Jeddah and did not enter ihram;
first of all he went to al-Madinah al-Munawwarah to visit the Prophet’s
Mosque, then he entered ihram from the miqaat of the people of Madinah. Is
that valid?

He replied: There is nothing wrong with
it. If a person comes from his country heading to Madinah first, and he
stops in Jeddah then goes from Jeddah to Madinah, then he comes back from
Madinah, entering ihram at the miqaat of the people of Madinah, there is
nothing wrong with that.

End quote from Liqa’ al-Baab al-Maftooh,
no. 121 

And Allah knows best.