One of the major critiques expressed by some Sunni scholars deals with the authenticity of news on Ghadir Khumm. They have either undervalued the narration or claimed the reasoning is incomplete to question the totality of the issue. Shahabuddin Alusi (1270 Lunar Year), adopting Ibn Kathir Dameshghi's view (774 Lunar Year) in Tafsir al-Qu'ran al-Azim[1] writes: "Ghadir Khumm is the most important reason of Shia Muslims to consider leadership of Islamic Ummah for Imam Ali (A.S). In order to realize their objectives, Shia Muslims have added words and sentences to the news on Ghadir Khumm event, composed poems and rebuked companions of the Prophet for ignoring the explicit rule of the Prophet. Bear in mind that the story of Ghadir Khumm, related to the leadership of Imam Ali (A.S), is not true or certain to the Sunni Muslims. On the other hand, Bukhari and Muslem have not narrated the story of Ghadir Khumm because of the lack of authenticity of the event; rather, recording of this event in the other books such as Abu Jafar Tabari in Tafsir Jami al-Bayan and Abulqassim Assakir in the History of Damascus has taken place along with other well- and low-documented hadiths. They have collected all traditions."[2]
Response:
The news on Ghadir Khumm are based on successive and convincing narrations, expressed by 110 companions and 84 followers in over 360 books by the scientists of various Islamic sects in detail and in brief. One of the renowned Sunni exegetists is Fakhr Razi who has expressed 10 lists of the narrations of the companions, followers and exegetists. The author of Ghayat al-Maram has brought together 89 narrations from Sunni hadiths and 43 narrations from Shia scholars along with related earlier documents. Alusi and Rashid Reza had better criticize the authenticity of the documents and the manners of narration without considering these issues. This is because when a certain narration is rejected despite solid evidences, how can one trust a single narration that some Sunni scholars accept and trust it. Therefore, rejecting documents on Ghadir Khumm is not in conformity with any criterion.[3]
Ibn Hajar Asqalani, one of the renowned Sunni scholars has opined on the credit and authenticity of Ghadir Khumm saying: "The tradition of "Whoever I am his Leader (mawla), Ali is his Leader (mawla)" was narrated by Termezi and Nessaei. This has been narrated by many and Ibn Uqdah (322 Lunar Year) in his book has brought a number of solid evidences in support of this claim
source : www.tebyan.net