Praise be to Allah.
No Muslim doubts that Allaah has forbidden alcohol and gambling, and He has described them as major sins. Allaah says (interpretation of the meaning):
“O you who believe! Intoxicants (all kinds of alcoholic drinks), and gambling, and Al‑Ansaab (stone altars for sacrifices to idols etc) and Al‑Azlaam (arrows for seeking luck or decision) are an abomination of Shaytaan’s (Satan’s) handiwork. So avoid (strictly all) that (abomination) in order that you may be successful.
91. Shaytaan (Satan) wants only to excite enmity and hatred between you with intoxicants (alcoholic drinks) and gambling, and hinder you from the remembrance of Allaah and from As‑Salaah (the prayer). So, will you not then abstain?”
When Allaah forbids a thing, He also forbids helping others to do it in any way whatsoever. Allaah says (interpretation of the meaning):
“Help you one another in Al‑Birr and At‑Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment”
The basic principle according to the scholars of sharee’ah is that the means are subject to the same rulings as the ends. Everything that leads to something haraam is also haraam.
It is not permissible for a Muslim to be present in a place where Allaah is disobeyed, unless that is because of necessity or he is forced to do that. He is obliged to denounce this evil and change it and remove it; if he cannot then he must leave that place. The basic principle is that the Muslim should shun sinful places and keep away from them, and not help the people there to disobey Allaah. Staying in such places goes against the command to the Muslim to change evil wherever he sees it, and it goes against the command to shun places of evil and sin.
Allaah says (interpretation of the meaning):
“And it has already been revealed to you in the Book (this Qur’aan) that when you hear the Verses of Allaah being denied and mocked at, then sit not with them, until they engage in a talk other than that; (but if you stayed with them) certainly in that case you would be like them.”
al-Qurtubi (may Allaah have mercy on him)said: “then sit not with them, until they engage in a talk other than that” means, other than kufr. “(but if you stayed with them) certainly in that case you would be like them” this indicates that it is obligatory to avoid keeping company with sinners if they openly commit evil, because the one who does not avoid them is approving of their actions, and approving of kufr is kufr. Allaah says: “(but if you stayed with them) certainly in that case you would be like them” so everyone who sits in a sinful gathering and does not denounce them, shares the burden of sin equally with them.
He should denounce them if they speak of sin and commit sin. If he is not able to denounce them then he should get up and leave, so that he will not be one of those mentioned in this verse.
It was narrated that ‘Umar ibn ‘Abd al-‘Azeez (may Allaah be pleased with him) caught some people who were drinking alcohol, and it was said to him that one of those who were present was fasting. He had him beaten in order to discipline him, and he recited this verse: “certainly in that case you would be like them” i.e., approving of sin is also sin.
End quote from Tafseer al-Qurtubi (5/418)
Shaykh Ibn Baaz (may Allaah have mercy on him) said:
Denouncing sin in one's heart is obligatory for every one, which means hating and despising the evil, and separating from those who commit sin if one is unable to denounce it with one's hand or tongue (i.e., by taking action or speaking out).
Al-Durar al-Saniyyah fi’l-Ajwabah al-Najdiyyah (16/142)
Moreover there is the fear that the one who works in these places will become weak in faith, and may lose all sense of gheerah (protective jealousy), and the shaytaan may tempt him to sin. Allaah says (interpretation of the meaning):
“O you who believe! Follow not the footsteps of Shaytaan (Satan). And whosoever follows the footsteps of Shaytaan (Satan), then, verily, he commands Al‑Fahshaa’ [i.e. to commit indecency (illegal sexual intercourse)], and Al‑Munkar [disbelief and polytheism (i.e. to do evil and wicked deeds; and to speak or to do what is forbidden in Islam)]”
Based on the above, it is not permissible for a Muslim to work in these casinos, because then he will helping others to disobey Allaah and approving of sin, or he will come under the ruling of one who approves of sin. That includes all those who work in these casinos, it includes those who play with the customers, or teach them, guard them, serve them, receive them and other jobs. The Muslim should not be deceived by the salary he gets, for on the Day of Resurrection he will be asked about his wealth, from where he acquired it and on what he spent it.
The most precious thing that a Muslim has is his religious commitment, so he must guard it and not be one of those who sold their religion for a trifling price of worldly gain which will soon pass away.
This is the ruling: it is haraam to work in these places; and in your case, it is even more haraam. Do you know why?
Because you are a woman, and you are less able to put up with things and resist than a man is, and the evildoers’ hopes of corrupting you will be stronger. How can a girl of your age be sure that she will be safe if she is among those deviants in those casinos with their alcohol, drunkenness and desires?
We hope that you will submit to sharee’ah and reason, and you will not go anywhere near those places, so as to protect yourself and the most precious thing that you possess.
Remember the words of Allaah (interpretation of the meaning):
“And whosoever fears Allaah and keeps his duty to Him, He will make a way for him to get out (from every difficulty).
3. And He will provide him from (sources) he never could imagine. And whosoever puts his trust in Allaah, then He will suffice him. Verily, Allaah will accomplish his purpose. Indeed Allaah has set a measure for all things”
And remember the words of the Prophet (peace and blessings of Allaah be upon him): “Whoever gives up something for the sake of Allaah, Allaah will compensate him with something better than it.” Classed as saheeh by al-Albaani. Do not forget that no soul will die until it has received its provision in full, sooner or later.
We ask Allaah to help you to forego this job willingly, and to compensate you with something better than it, and to bestow His bounty upon you, and to make us and you independent of means through halaal ways so that we have no need of that which is haraam.
And Allaah knows best.