Shama-il Tirmidhi Chapter 8, Hadith Number 14 (66).

Samurah bun Jundub (R.A) says: “Rasulullah (S.A.W) said, “Wear white clothing because it is more taahir (paak) and clean, and also clothe your dead in it.”

By ‘It is more taahir (paak) and clean is meant that if a small stain appears, it will show clearly, whereas in coloured clothing it does not show easily.