‘A'isha said that the Prophet liked to begin with the right as much as possible in all his affairs, in his purification, combing his hair, and putting on his sandals. (Bukhari and Muslim.)
The Virtue of Beginning with the Right
This noble hadith from the Mother of the Believers, 'A'isha (may Allah be pleased with her), establishes a comprehensive principle in the Sunnah: the preference for beginning with the right side in all permissible matters. This is not merely a recommended act (mustahabb), but a consistent practice (sunnah fi'liyyah) of the Prophet (peace be upon him) that he adhered to "as much as possible."
Scholarly Commentary on the Acts Mentioned
In his purification (at-tahur): The scholars deduce from this that one should begin with the right limb when performing wudu (ablution), such as washing the right hand before the left, and the right foot before the left. This applies to all acts of purification that involve paired limbs.
Combing his hair (mughtasilihi): This indicates starting to comb from the right side of the head. The wisdom includes seeking blessings, displaying neatness, and differentiating the acts of the believers from others. It brings order and beauty to one's appearance in a manner beloved to Allah.
Putting on his sandals (wa fi na'lihi): One should put the right sandal or shoe on first. Conversely, when removing them, one begins with the left foot first. This practice imbues mundane acts with the remembrance of Allah and His guidance.
The Underlying Wisdom and Legal Ruling
The phrase "in all his affairs" shows the generality of this principle, extending to wearing clothes, entering mosques, eating, drinking, and giving and receiving items. The right side is honored in the Shari'ah, as it is the side of the people of Paradise, while the left is for others.
The legal ruling is that this is a confirmed Sunnah (Sunnah mu'akkadah). While neglecting it is not sinful, adhering to it earns great reward for following the exemplary conduct of the Prophet (peace be upon him). It is a means of having one's life conform to divine patterns, making every action an act of worship.