Why Did Allah Specify Following the Millah of Ibrahim?

[Ibn Abi Ahmed]

"...Allah specified His Prophet, Ibrahim, that the religion of Islam - in its general meaning - is his millah, such as is mentioned in His Saying: {"Say: 'Allah has Spoken the truth. So, follow the millah of Ibrahim, purely.'"} [Al 'Imran; 95] for the following reasons:

First: Ibrahim faced a great deal of hardship in the course of establishing Tawhid and destroying shirk, and being given victory from Allah in doing this, as mentioned by Allah throughout the Qur'an.

Second: Allah - the Exalted - placed the Book and Prophethood in his progeny, and this is why he is referred to as "father of the Prophets," and this is why Allah Said: {"...the millah of your father, Ibrahim..."} [al-Hajj; 78]

And he - peace be upon him - is the origin of seventeen Prophets that Allah mentioned in His Book as being from his progeny, and they are:

-his son, Isma'il, from whose progeny came Muhammad;

-his son, Ishaq, from whose progeny came Ya'qub, Yusuf, Ayyub, Dhu al-Kifl, Musa, Harun, Ilyas, al-Yas', Yunus, Dawud, Sulayman, Zakariyyah, Yahya, and 'Isa;

Third: to answer the claims of the Jews and Christians that they are upon the millah of Ibrahim, as Allah has showed them to be liars in this, Saying: {Or say you that Ibrahim, Isma'il, Ishaq, Ya'qub, and the twelve sons of Ya'qub, were Jews or Christians? Say: 'Do you know better, or does Allah? And who is more unjust than he who conceals the testimony he has from Allah? And Allah is not unaware of what you do.'"} [al-Baqarah; 140]..."

[From Bakr Abu Zayd's 'al-Ibtal'; p. 32]