Imam Ali (AS) said:

Indeed, the people are in two groups; one group are the followers of the religion, and the others are heretics/innovators who do not have any proof of the Prophet’s (PBUH) Sunnah (traditions) from God nor have any light from proofs of the truth (they follow their own personal opinions and inappropriate desires of their own souls) [1].

[1] Nahjul Balaghah, Sermon 176.

Source: en.shafaqna.com