Hadith - Al-Tirmidhi 4623, Narrated 'Aisha, r.a.
Allah's Messenger (peace be upon him) was questioned about Waraqah and Khadijah said to him, "He believed in you, but died before you appeared as a prophet." Allah's Messenger (peace be upon him) then said, "I was shown him in a dream, wearing white clothes, and if he had been one of the inhabitants of Hell he would have been wearing different clothing." [Ahmad and Tirmidhi transmitted it]

Hadith - Sahih Al-Bukhari 7.717, Narrated Abu Dharr, r.a.
I came to the Prophet while he was wearing white clothes and sleeping....