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”