Shama-il Tirmidhi Chapter 10, Hadith Number 8 (78).
Jaabir radiallahu anhu says that Rasulullah Sayyidina Rasulullah sallallahu alaihe wasallam. prohibited eating with the left hand, or the wearing of one shoe only.
According to the majority of the ulama the fulfilment of these commands are meritorious, that means, not haraam. Some ulama of the Zaahir have stated that it is prohibited to act contrary to this.