To what extent can we rely on Ibn Ishaq's Sirat? Is the account of Quraish leaders proposing wealth, women, and kingship to Muhammad (pbuh) in exchange for renouncing his prophethood authentic?
1- The book known as Seerat Ibn Is-haaq سيرة ابن اسحاق was complied by order of the Abbasside Khalif Abu Ja’far Al-Mansour who was a staunch enemy of Ahlul Bayt (AS) and he killed Imam Al-Sadiq (AS) and many pious persons from the family of Ahlul Bayt (AS). Abu Ja'far Al-Mansour did a lot against Ahlul Bayt and tried to create a new sect (Maliki sect) to drive Muslims away from Ahlul Bayt (AS). 2- No doubt, Ibn Is-haaq was trying to please Al-Mansour in his book.
3- Ibn Is-haaq narrated from Ibn Shihaab Al-Zohra who spent long years from his life in serving Bani Omayyah.
4- We don't take all the book of Ibn Is-haaq as authentic but we take from it the admission from them about few facts in the early history of Islam which they try to deny in other books.
5- Seerat Ibn Hishaam (Died 213 Hijri) is the modified copy from Seerat Ibn Is-haaq (Died 151 Hijri) and it is very famous as one of the very old books in history of the Prophet Muhammad (SAWA).
Wassalam.