What is obligatory upon the Muslim during Hajj

Question :

What is obligatory upon the Muslim during the performance of the obligation of Hajj ? Is it permissible for him to busy himself with other matters that are outside the realm of worship?

Answer:

It is obligatory upon him to be mindful of what Allâh has made obligatory upon him. This includes strictly guarding the performance of the prayers in their proper times in congregation, commanding the good and forbidding the evil, calling to Allâh with wisdom and good preaching and avoiding what Allâh has made forbidden for him. This is due to Allâh's Statement :

"So, whoever intends to perform Hajj therein (by assuming Ihram), then he should not have sexual relations (with his wife), nor commit sin, nor argue unjustly during the Hajj."

And there is the statement of the Prophet:
"Whoever performs Hajj and he does not have sexual relations (with his wife) or commit sins, he will return (after Hajj) like the day that his mother gave birth to him (i.e., without sin)."

The word 'Rafth' means to have sexual intercourse while in Ihram and those things that lead to it from speech and actions. The word 'Fusuq' means all acts of disobedience. This is also because the obligation upon the Muslim in every time and place is that he fears Allâh, strictly observes that which Allâh has made obligatory upon him and avoids what Allâh has made forbidden for him. Hence, if he is in the Sacred Land of Allâh and involved in performing the rites of Hajj, then the obligation upon him is even greater and more severe. His sin in doing what Allâh has forbidden for him is even greater and more serious. It is permissible for him to buy and sell and other things from that which Allâh has allowed for him of statements and deeds. This is due to Allâh's Statement:
"There is no sin on you all that you seek some bounty (i.e., business and trade) from your Lord."

Ibn 'Abbas and others said in explaining this Verse: "This means during the times of Hajj." This is from the bounty of Allâh and His mercy, and it is part of His easing matters for His servants and being kind to them. For verily, the Hajj pilgrim is in need of this. And Allâh is the Giver of success.

Source:
Ash-Shaykh Ibn Baz
Fatawa Islamiyah, Vol. 4 Pages 37-38