Shama-il Tirmidhi Chapter 004, Hadith Number 003 (033).
Hadith Section/Book: Shama-il Tirmidhi Chapter 04. The Combing Of The Hair Of Rasoolullah
Hazrat Aisha (Radiallahu anha) says, "Sayyidina Rasulullah (Sallallahu alaihe wasallam) liked to begin with the right while combing his hair; while performing ablution (wudhu) and when putting on his shoes. (Also in every other deed, he first began with the right then the left).
This (beginning from the right) is not confined to the three acts mentioned in this Hadith. Sayyidina Rasulullah (Sallallahu alaihe wasallam) began everything with the right, that is why every other deed' has been added in the translation of the Hadith. The basic rule is, that all those things that reflect dignity and elegance, while putting on these the right is preferred, and when removing them the left is begun with, as when putting on clothes, shoes etc. When one enters the Masjid, one enters with the right foot and leaves with the left foot first, as this is the place of dignity and greatness. Contrary to this, in those things that do not have elegance in them, for instance when entering the toilet.