The Messenger of Allah (ص) said:
“Whoever obeys me has obeyed Allah, and whoever disobeys me has disobeyed Allah, and whoever obeys Ali has actually obeyed me, and whoever disobeys Ali has disobeyed me"
Hakim Naishapuri, Al-Mustadrak, V.3, page 121. Hakim Naishapuri says: "The chain of narration of this hadith is authentic and the author of Kanz al-Ummal has narrated from Abuzar that the Prophet (s.a.w.a.) said, "Whoever disassociates from you has disassociated from me, and whoever disassociates from me has indeed disassociated from Allah." Refer to Muttaqi Hindi, Kanz al-Ummal, V.11, page 614.