He is Ibrahim ibn Hassan al Muthanna, third of the sons from Fatimah bint Hussain rahimaha Llah.
Agnomen: His agnomen was Abu al Hassan, some have said Abu Ismail.
Title: He was given the title al Ghamr (generous) due to his excessive generosity.
He had a close resemblance to the Prophet salla Llahu ‘alayhi wa sallam.
He was also amongst those who were imprisoned and tortured by Abu Jafar al Mansur. He was martyred in prison alongside his brothers in 145 A.H. his age at the time was 69.
Abu al ‘Abbas al Saffah would honour him during his era.
He and his children suffered immensely at the hands of Mansur al Dawaniqi. One of his sons named Muhammad, whose mother was an Umm Walad named ‘Aliyyah, who was known as Al Dibaj al Asghar (or al Dibaj junior) on account of his handsomeness was questioned by Mansur:
Mansur asked, “Are you al Dibaj al Asghar?”
Muhammad replied, “Yes I am.”
Mansur said, “As for you, by Allah, I am going to kill you in a manner that I have not killed anyone else from your family.”
He then ordered that a pillar be hallowed, and Muhammad placed in it thereafter. It was then sealed upon him whilst he was alive.
There is an incident which has been reported which illustrates his wisdom: Al Saffah would often bother ‘Abdullah al Mahd about the whereabouts of his sons, Muhammad and Ibrahim, which ‘Abdullah complained about to his brother, Ibrahim al Ghamr:
Ibrahim said, “If he asks you this again then tell him that their uncle knows more about them.”
‘Abdullah asked him, “Will you be fine with that?”
Ibrahim replied, “Yes.”
So al Saffah asked al Mahd about his sons one day and he replied, “I do not know much but their uncle knows quite a bit about them.”
So al Saffah summoned Ibrahim to ask him about them.
Ibrahim said, “Should I respond as a man converses with his king or as one converses with his cousin?”
Al Saffah replied, “As one converses with his cousin.”
Ibrahim said, “I implore you by Allah, O Amir al Mu’minin, if Allah has preordained that Muhammad and Ibrahim should take charge of this affair and you in return endeavour along with all the people on the earth to prevent it, will you all be able to prevent it?”
Al Saffah replied, “No, [we will not be able to].”
Ibrahim then said, “Then why this embitterment towards this Sheikh for the bounties he has been granted?”
Al Saffah replied, “I will never bring it up after today.”
And he did not mention it again until they were separated by death.
The scholars have praised Ibrahim al Ghamr:
These are the sons of Sayyidina Hassan al Muthanna and Sayyidah Fatimah bint Hussain radiya Llahu ‘anhum.
Ibn al Taqtaqi has reported with his chain of narration from Abu Muhammad Qasim ibn ‘Abdur Razzaq:
Manzur ibn Zaban—who is the maternal grandfather of Hassan al Muthanna—came to Hassan ibn Hassan and said to him, “Perhaps you have left a progeny after me?”
Hassan replied, “Yes, I married my paternal cousin, daughter of Hussain.”
Manzur said, “You have not done well, do you not know that if family members marry than children are not conceived. If would have been better for you to have married amongst the [some other] Arabs.”
Hassan responded, “Verily Allah has blessed me with a son from her.”
He asked to see the child, and ‘Abdullah al Mahd was brought before him. He was pleased with him and this brought him joy.
Manzur then said, “You have done well, by Allah, this is a lion who will be victorious.”
Hassan said, “I have been blessed with another son from her.”
Manzur said, “Show him to me.”
Hassan [al Muthallath] was then brought before him, and he was pleased with him.
Manzur then said, “You have done well, [but] he is not equal to the first.”
Hassan said, “I have been blessed with a third son from her.”
Manzur said, “Show him to me.”
Ibrahim [al Ghamr] was then brought before him, and he was pleased with him.
Manzur then said, “You do not need to go to her after this one.”
This narration gives us an indication of their lofty status.
As for the children of Sayyidah Fatimah bint Hussain rahimaha Llah from Sayyidina ‘Abdullah ibn ‘Amr ibn ‘Uthman ibn ‘Affan: they are Muhammad al Dibaj, Qasim, and Ruqayyah.
 Al Dhahabi: Tarikh al Islam, incidents of the year 144 A.H; Al Bidayah wa al Nihayah, 10/82; Maqatal al Talibiyin, pg. 173-181; Al Asili fi Ansab al Talibiyin pg. 112; Muntaha al Amal 1/358; ‘Umdat al Talib fi Al Abi Talib, pg. 283.
 Muhammad al Nafs al Zakiyyah and his brother Ibrahim, sons of ‘Abdullah ibn Hassan. They both had opposed al Saffah and his rule but they only led their rebellion during the era of al Mansur al Dawaniqi. They were both martyred in 145 A.H.
 ‘Umdat al Talib, pg. 283-285. In the narration of al Mizzi in Tadhib al Kamal the narration contains the name Hassan al Muthallath in place of Ibrahim al Ghamr, as mentioned under the biography of Hassan ibn Hassan ibn ‘Ali.
 Al Asili, pg. 112; ‘Umdat al Talib, pg. 283.
 Muntaha al Amal, 1/358. Al Khatib al Baghdadi has written his biography in Tarikh Baghdad, 6/45.
 Al Asili, pg. 112.
 The books of history and biographies have not provided us with much detail about their lives except that Zainab was married to one of the Khalifas of the Banu Umayyah.