Hawzah News Agency - Imam al-Kazim (AS) said:

إنَّ للَّهِ‏ِ عَلَى النّاسِ حُجَّتَينِ: حُجَّةً ظاهِرَةً، وحُجَّةً باطِنَةً، فأمّا الظّاهِرَةُ فَالرُّسُلُ والأنبِياءُ والأئمَّةُ عليهم السلام، وأمّا الباطِنَةُ فَالعُقولُ.

‘Verily Allah has two authoritative proofs over people: a manifest proof and an inward proof. The manifest proof is represented by the prophets and messengers and Imams (AS), and the inward proof is represented by the intellects.’

Alkafi. p. 16, no. 12