aź-Źahabī, may Allah have mercy upon him said in the Siyar Alā-A’lām an-Nubalā’:
The Imām, the Hāfizh, the ‘Allāmah, Sheikh al-Islām Abū Bakr Muhammad Bin Ibrāhīm Bin al-Munźir an-Naisābūrī , the Faqīh, resident of Makkah, author of works such as al-Isyrāf fī Ikhtilāf al-‘Ulamā’, the book al-Ijmā’, the book al-Mabsūt and others.
He was born at the time of the death of Ahmad Bin Hanbal.
He narrated from ar-Rabī’ bin Sulaimān, Muhammad Bin abd Allāh bin ‘abd al-Hakam, Muhammad Bin Ismā’īl aś-Śā’igh Muhammad Bin Maymūn, ‘Ālī Bin ‘abd al-‘Āzīz and many others mentioned in his books.
Those who narrated from him includes Abū Bakr Bin al-Muqri’, Muhammad Bin Yahya Bin ‘Ammār ad-Dimyāti, as well as Al-Husain and al-Hasan sons of ‘Alī Bin Sya’bān.
al-Hākim did not mention him in his Tarīkh, forgetting him. Neither was he mentioned in Tārīkh Baghdād nor Tārīkh Dimashq for he indeed did not enter it.
He is regarded as one of the shafiite fuqhahā’. asy-Syeikh Muhyi ad-Dīn an-Nawāwī said:
He has, from amongst the tahqīq in his books, what no other can ever come close to. He is at the limit with respect to mastery in the knowledge (ma’rifah) of Hadīth. He has ikhtiyār and thus is not tied in the ikhtiyār to a maźhab in essence. Rather, he pivots about the żāhir (apparent) of the proofs.
I say: One is not tied to a single maźhab except those who are qāśir (fall short) in mastery of knowledge (‘ilm) as per the majority of ‘ulamā’ in our age or one who is ta’āśub (a zealot). This Imām is from amongst those bearers of hujjah, parallel in the arena of Ibn Jarir, Ibn Suraij and the likes, may Allah have mercy upon them all.
‘Umar bin ‘abd al-Mun’im reported to us,
Abū al-Yumn al-Kindī reported to us in the year 680 in writing
‘Alī Bin Hibah Allāh Bin ‘abd as-Salām reported to us
al-Imām Abū Ishāq narrated to us in the book al-Tabaqāt who said:
Abū Bakr Muhammad Bin Ibrāhīm Bin al-Munźir an-Naisaburi is amongst them. He passed away in Makkah in the year 309 or 310 AH. He wrote several books with regard to ikhtilāf (differences of opinion) amongst the ‘ulamā’. No one has wrote in its likes. Those in agreement and opposition are in need of his books. I do not know from whom he took fiqh.
I say: He in fact took from the ashāb of Imām asy-Syāfi’ī . And what is mentioned by asy-Syeikh Abū Ishāq about his death is on the basis of tawahhum (conjecture). Otherwise, Ibn ‘Ammār certainly heard from him in 316 AH. al-Imām Abū Hasan Bin Qattān al-Fāsī dated his death to be on 318 AH.
A group reported to us with permission,
from ‘Āisyah Bint Ma’mar (ح)
Ahmad Bin Muhammad al-‘Allānī said
Ishāq Bin Abū Bakr reported to us
Yusuf Bin Khalīl reported to us
al-Muayyid Bin al-Ukhuwwah reported to us:
They both said:
Sa’īd Bin Abū ar-Rajā’ reported to us
Abū Tāhir Ahmad Bin Mahmūd and Manśūr Bin al-Husain reported to us
They both said:
Abū Bakr Muhammad Bin Ibrāhīm reported to us
Muhammad Bin Ibrāhīm bin al-Munźir, the Faqīh of Makkah reported to us
Muhammad Bin Maimūn narrated to us
‘abd Allāh Bin Yahya al-Burrullusī from Haiwah Bin Syuraih, from Ibnu ‘Ajlān, from Abū az-Zinād , from al-A’raj, from Abū Hurairah from the Prophet, Salutations of Allāh and His Peave upon him said:
مَنْ جَرَّ لِنَفْسِهِ شَيْئًا لِيَقْتُلَهَا ، فَإِنَّمَا يَجْعَلُهَا فِي النَّارِ ، وَمَنْ طَعَنَ نَفْسَهُ بِشَيْءٍ ، فَإِنَّمَا يَطْعَنُهَا فِي النَّارِ ، وَمَنِ اقْتَحَمَ ، فَإِنَّمَا يَقْتَحِمُ فِي النَّارِ
One who brought anything upon himself to kill it, then he has indeed made it in the fire. And one who stabs himself with anything, he has indeed stabbed it into the fire. One who plunged, indeed he plunges into the fire. (gharīb)
Ibn al-Munźir has a tafsīr which is huge, 10+ volumes. He is accomplished as an Imam of Ta’wīl as well.
 Taqiyuddin as-Subkī mentioned in his Tabaqāt al-Kubrā:
The four Muhammadūn are: Muhammad Bin Naśr, Muhammad Bin Jarīr, Ibn Khuzaimah and Ibn al-Munźir, from our aśhāb. They reached the level of mujtahid mutlaq but it does not exclude them from being one of the aśhāb of asy-Syāfi’ī. They are trained on the basis of his uśūl, but departed from his maźhab if they went beyond it.
 Amongst his shuyūkh are
(1) al-Hasan Bin Muhammad az-Za’farānī al-Baghdādī (d:259 AH), one of the narrators of the Maźhab asy-Syāfi’ī al-Qadīm.
(2) Muhammad Bin ‘abd Allāh al-Miśrī al-Mālikī (d:268 AH), an aśhāb of Imām asy-Syāfi’ī.
(3) al-Rabī’ Bin Sulaimān al-Murādī (d: 270 AH), a companion of Imām asy-Syāfi’ī and a narrator of his books.
(Preface to al-Asyrāf, Maktabah Makkah ath-Thaqafiya)