We find in the Sunni Hadith book, Mustadrak `ala Al-Sahihain, by Al-Haakim, a beautiful hadith regarding Imam Ali (as):

The Messenger of Allah (sawa) said: “Looking at Ali (as) is worship”

Source: Mustadrak `ala Al-Sahihain, Al-Haakim, Volume 3, Page 152 (See Image)

Grading: This hadith has been graded by the Sunni Al-Haakim as Sahih/Authentic.

Two other hadiths with slight variations occur following the above hadith, both saying “Looking at the face of Ali (as) is worship”