Hajj, is it required?
Hajj is one of the five pillars that Islam is built upon; Allah, the Exalted, says: "And Hajj to the House is a duty that mankind owes to Allah, those who can afford the expenses; and whoever disbelieves [i.e., denies Hajj (pilgrimage to Makkah), then he is a disbeliever of Allah], then Allah stands not in need of any of the `Alamin (mankind, jinn and all that exists).'' (3:97)
Ibn `Umar (May Allah be pleased with them) reported: The Messenger of Allah (Peace Be Upon Him) said, "(The superstructure of) Islam is based on five (pillars), and mentioned the pilgrimage to the House.'' [Al-Bukhari and Muslim].
Abu Hurairah (May Allah be pleased with him) reported: The Messenger of Allah (Peace Be Upon Him) delivered a Khutbah and said, "O people! Hajj (pilgrimage to the House of Allah) has been made incumbent upon you, so perform Hajj.''
Hajj is compulsory at least once in a lifetime for those who have the means.