What is the sign of Hajj having been accepted by Allah Ta'ala?

Answer

On his return home, his moral life improves. He progresses spiritually. This indicates acceptance of his Hajj. If a person who has performed Hajj, again lapses into his former sinful life after returning from Hajj, then it will be a sign that Allah Ta'ala has not accepted his Hajj. Obviously, a person who sins after Hajj, acquits himself with greater treachery, hence he is deserving of greater punishment.