Q. 381. Is every person who extends his hand for Zakah deserving of it?
A. Not every person who extends his hand for Zakah is deserving of it, because there are those among mankind who extend their hands for money while they are wealthy. This type of person will come on the Day of Resurrection while his face will not have a bit of flesh on it,  may Allah protect us from that. He will come on the Day of Resurrection, on the Day when the witnesses will stand and the bones of his face will be visible, may Allah protect us from that, and the Prophet (صلى الله عليه و سلم) said:
“He who begs the riches of others to increase his own wealth is asking only for burning coals (in the Hereafter), so let him ask a little or much.” 
I would like to take this opportunity to warn those people who ask people in an importune manner when they are in possession of wealth. Indeed, I warn everyone who accepts Zakah when he is not entitled to receive it. I say to him: If you took Zakah to which you are not entitled, you are only consuming ill-gotten gains, may Allah protect us from that, and a person should fear Allah, for the Prophet (صلى الله عليه و سلم) said:
“Whoever tries to make himself self-sufficient, Allah will make him self-sufficient; and whoever abstains from asking others, Allah will make him content” 
But if a man extends his hand to you, and you believe it is most likely that he is entitled to it, and you gave him, then the Zakah will be counted, and you will have discharged your obligation, even if it became apparent after that that he was not entitled to it. There is no need to think that you have to pay the Zakah again (to someone else).
The evidence for this is the story of the man who gave money in charity, and he gave charity first to a prostitute and the people began to talk, saying: “Have you given money tonight to a prostitute?” He said: “All praise and thanks are to Allah.”
Then he gave charity on the second night and it fell into the hands of a thief and the people began to talk, saying: “Have you given money tonight to a thief?”
Then he gave charity on the third night to a rich man and the people began to talk, saying: “Have you given money tonight to a rich man?” He said: “All praise and thanks are to Allah for the prostitute, the thief and the rich man.”
Then it was said to him (by an angel): “Your charity has been accepted; as for the prostitute, haply (i.e perhaps) she may content herself with what you have given her and it may prevent her from committing illegal sexual intercourse, while as for the thief, haply he may content himself with what you have given him and he may refrain from stealing, while as for the rich man, haply, he may reflect and give charity” 
So, my brother, look at the honest intention, what is its effect: Therefore, if you gave the person who asked you, and then it became apparent that he was wealthy and you had given him something, believing that he was poor, it is not necessary for you to repay the Zakah.
[l] Reported by Muslim in the Book of Zakah, in the Chapter: The Disapproval of Begging From the People (1040)
 Reported by Muslim in the Book of Zakah, in the Chapter: The Disapproval of Begging From the People ( 1041 ).
 Reported by Al-Bukhari in the Book of Zakah, in the Chapter: There is no Obligation to Give Charity Except Upon One Who is Wealthy (1427); and by Muslim in the Book of Zakah, in the Chapter: The Virtue of Contentment and Patience (1053).
 Reported by Al-Bukhari in the Book of Zakah, in the Chapter: If One Unwittingly Gave Charity to a Rich Person ( 1421 ); and by Muslim in the Book of Zakah, in the Chapter: Confirmation of the Reward of One Who Gives Charity, Even if the Charity Fell into the Hands of One Who is not Entitled to it (1022).
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Fatawa Arkanul-Islam – Islamic Verdicts on the Pillars of Islam (Volume Two) – Prayer, Zakah, Fasting, Hajj
By the Honorable Shaikh Muhammad bin Salih Al- ‘Uthaimeen
Collected and Arranged by Fahd bin Nasir bin Ibrahim As-Sulaiman
Published by Dar-us-Salam