Ref: www.seratonline.com
Imam Kazim (a.s.) said, ‘Allah has not emphasized anything to His servants like He has emphasized about testifying Imamat (of the Imams of the Ahle Bait) and the servants have not rejected anything like they have rejected Imamat.’
Qurabul Asnaad page 123
Imam Reza (a.s.) was asked, ‘One who dies without an Imam for himself dies the death of ignorance?’ Imam (a.s.) replied, ‘Yes, and the Waaqifi (deniers of Imam Reza’s (a.s.) Imamat) are disbelievers and the Naasibi (enemies of Ahle Bait (a.s.)) are Mushrik.’
Ikmaaluddin page 375
Regarding the Quranic verse, ‘And your Lord creates and chooses whom He pleases…’ Imam Sadiq (a.s.) said, ‘Allah chose Muhammad and His Ahle Bait (a.s.).’
Manaaqib-e-Aale Abi Talib volume 1, page 316
Imam Sadiq (a.s.) said, ‘One who dies without an Imam for himself dies the death of apostasy, deviation and hypocrisy.’
Mahaasin page 155
Imam Sadiq (a.s.) said, ‘The Holy Prophet (s.a.w.a.) was raised to the heavens on 120 occasions and on each occasion Allah emphasized the (importance of) Wilayat of Ali (a.s.) and the Imams (a.s.) more than any other religious obligation.’
Khesaal volume 2, page 149
Imam Baqir (a.s.) said, ‘Ali asked the Holy Prophet (s.a.w.a.) — O Prophet of Allah! Are the guides from amongst or us or other than us? The Holy Prophet (s.a.w.a.) replied, ‘All the guides until the Day of Resurrection are from us. Through us Allah will rescue the people from the deviation of polytheism (Shirk) and from us Allah will rescue the people from the deviation of discord (Fitna) and through us they will become brothers after deviation.’
Ikmaaluddin page 134