What is the hajj? What is the wisdom of hajj?
Hajj is a type of worship that Muslims who have the requisite wealth and health perform by visiting the Kaaba in Mecca during certain days, once in their lifetime, and by performing certain rituals. People observe much worship, supplication, and remembrance of Allah in Hajj. They remember Allah in their every move and establish His love in their hearts. They also obtain good characteristics such as humbleness, helplessness, patience, submission, abnegation, sincerity, discipline of time and action, preparation for death and the Day of judgment, not to harm any plant or living being, and not to think badly about anybody. This is because Hajj, which outwardly revolves around certain symbols, in fact consists of different actions in different places that entail various spiritual practices. Everyone benefits from each of its several aspects.
Hajj redirects a person wholly to a spiritual life. This is because this sensitive type of worship is filled with manifestations of compassion, mercy, and love such as not hunting, not even to kill a fly, not to pull off even a green leaf, and not to hurt the creation of Allah.
Muslims who go to Hajj stand in spiritual unity by getting together at the same time and place. Concepts such as country, race, color, clothes disappear, and Islamic brotherhood replaces them. There, chairman of the board and worker, rich and poor, knowledgeable and ignorant, ruler and subject are all together, all in the same clothes, in the same square, and in the same row. Muslims listen to each other’s troubles and problems there and send messages to their brothers who are afar.
 For details on worship see http://www.islamicpublishings.net/images/book/ingilizce/islamimanibadet_ing.pdf.
Source: Dr. Murat Kaya,The Final Divine Religion: ISLAM