Is this hadith authentic?

[Qamar Farooq]

Assalamualakum

There is a hadith going around the internet that states "Whoever contests `Ali in regard to the khilafah is an unbeliever." Ibn al-Maghazili in his Manaqib (Tehran), p.45, from Abu Dharr al-Ghifari, and`Allamah `Ayni Hyderabadi in Manaqib Sayyidina `Ali (A`lam Press, Charminar), p.52, from al-Khatib al-Khwarazmi and Ibnal-Maghazil

Is this hadith authentic?