He intended to do Hajj for himself, then he decided to change his intention and do it on behalf of a relative of his. Is it permissible for him to do that?

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Check below answers in case you are looking for other related questions:
Reason for circulating the Ka'bah counterclockwise
He is suggesting that Mina be expanded!

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Related Answers:
Difficulties of Hajj
Is it mustahabb for everyone who wants to enter ihram for Hajj or ‘Umrah to stipulate a condition?
A boy died and had not done Hajj; can Hajj be done on his behalf?
Reason for circulating the Ka'bah counterclockwise
He is suggesting that Mina be expanded!

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