Maulana Hakeem-ul-Ummah Ashraf Ali Thanvi Sahab (r.a.) highlights in his notorious work Bahishti Zewar a few Virtues of Hajj. To read the rest you need to click on the link at the bottom of this post.
“1. It is mentioned in a Hadith that the angels shake the hands of those hajis who go for hajj by some means of transport, and they embrace those who go for hajj on foot.
2. It is mentioned in a Hadith that when a person goes for hajj on a camel, for every step that the camel takes the person will receive 70 rewards. And the person who goes for hajj on foot will receive 700 rewards for every step that he takes. Although the Hadith mentions “camel”, the same will apply to other forms of transportation as well.
3. It is mentioned in a Hadith that the person who goes for hajj and the person who is waging jihad are actually the guests of Allah Ta’ala. If they make any dua to Him, He accepts it. If they seek forgiveness from Him, He grants it.
4. It is mentioned in a Hadith that the person who performs his hajj will intercede on behalf of 400 family members on the day of judgement. Apart from this, he will be purified of all his sins just as he was pure of sins when his mother had given birth to him. This is on the condition that his hajj is accepted. It is therefore incumbent on a person to ensure that this great ibaadah be accomplished through halaal earnings and that all the rites are fulfilled in the best manner possible. O Allah! Bless me with such a hajj as well. Aameen.
The forgiveness of sins as mentioned in the above Hadith does not apply to huquq (duties and obligations) such as those forms of ibaadah which one has to make qada of or debts which one has to fulfil. Ibaadaat which one has to make qada of or debts which one has to pay have to be fulfilled because these are not sins but huquq (rights).
5. It is mentioned in a Hadith that the person who goes on hajj with haraam wealth, and then recites the following dua:
Translation: O Allah! I have presented myself over here in obedience to Your command.
(which is among the duas that have to be recited during hajj) Allah Ta’ala replies to this dua by saying:
Translation: “I do not accept your labbayk nor your sa’dayk. And your hajj has been flung back onto your face.”
In other words, you have not presented yourself over here in obedience to My command. For, if you had presented yourself in obedience to My command, you would have spent your halaal wealth and come. Your hajj is not accepted because you have come to this great and pure place of Mine with your filthy wealth. You will not be fully rewarded although you will be absolved of your fard duty.
6. It is mentioned in a Hadith that when you meet a haji, make salaam to him, shake his hands, and ask him to make dua for forgiveness on your behalf. You should do this before he can even enter his house, i.e. the moment he returns from his hajj. You should ask him to make this dua for you because his sins have been forgiven. The person who returns from hajj is an accepted person in the sight of Allah Ta’ala. There is, therefore, great hope in his duas being accepted. Inform him of whatever dua you wish him to make on your behalf irrespective of whether it be for this world or for the hereafter. However, you should do this before he can reach his house.”