It is important to give zakat to those who are eligible to receive it. The recipients of the zakat are the following eight groups mentioned in the 60th ayah of Surah al Tawba:
"The alms are only for the poor and the needy, and those who collect them, and those whose hearts are to be reconciled, and to free the captives and the debtors, and for the cause of Allah, and (for) the wayfarers; a duty imposed by Allah. Allah is knower, Wise." (Surah al Tawba: 60).
As to your friend who is in need of money for marraige;
If he is in one of the following groups mentioned in the ayah, there is no harm in giving your zakat to him. These eight groups and their explanations are as following:
1. The poor
2. The needy (extremely poor)
3. Collectors of zakah
4. Those whose hearts are to be reconciled
5. Slaves, captivates
7. Fighters in the Way of Allah's (swt) holy service (fee sabeel illah)
8. The travelers.
Who are the poor?
In Islam, the poor are those whose property are below “the amount of Nisab” or as much as the value of Nisab, but not enough for their basic necessities.
In Islam a person is accepted as rich on condition that he owns one of the followings which are also the “amount of nisab”: 80,18 gram gold or money or commercial property costing as much as 80,18 gram gold; 40 sheep or goats; 30 cattle; 5 camels.
Who are the needy?
The needy are extremely poor people who possess no wealth whatsoever.
Who are the collectors of zakah?
They are the officers appointed by an Islamic Head of State or Government to collect zakat and zakat al fitr from the public. They are eligible to receive zakat even though they are wealthy.
Who are those whose hearts are to be reconciled?
They are those indicated by Prophet Muhammad (pbuh) as eligible to pay zakah for three reasons:
1. To reconcile their hearts to Islam and enable them to come to believe in Islam.
2. To prevent them from giving harm to Islam.
3. To strengthen their faith and enable them to proper Muslims.
Who are the slaves?
This group includes the slaves whose masters have agreed to set them free on the condition of a payment of a fixed amount. Zakat may be used to purchase their freedom.
Who are the debtors?
Debtors are those whose debts are above their property so that they are unable to pay their debt.
Who are the fighters in the way of Allah (swt)?
They are the poor soldiers who have dedicated themselves to fight in the way of Allah (swt) to dignify the glory of Islam.
Who are the travelers?
Travelers are those who stranded far from their homes, their properties and unable to reach their money. They are eligible to receive zakat even though they are wealthy at their residences.