He works as the deputy manager in a hotel that sells alcohol – what is the ruling on his work?

It is not permissible to work in a hotel in which sins are
committed, such as drinking alcohol, zina and so on, because it is helping
in sin and transgression and failing to denounce evil. 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. Surely, Allaah will collect the hypocrites and
disbelievers all together in Hell”

[al-Nisa’ 4:140] 

Al-Qurtubi said: The words of Allaah “then sit not with
them, until they engage in a talk other than that” mean something other
than kufr. “(but if you stayed with them) certainly in that case you
would be like them” this indicates that it is essential to avoid sinners
if they are committing evil openly, because the one who does not avoid them
is approving of their actions, and approving of kufr is itself kufr. Allaah
says “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
with them.  

He should denounce them if they speak sinful words or commit
sinful actions; if he is not able to denounce them then he should get up and
leave them, so that he will not be among the people mentioned in this
verse. 

It was narrated that ‘Umar ibn ‘Abd al-‘Azeez (may Allaah be
pleased with him) caught some people drinking alcohol, and it was said to
him that one of the people present was fasting, but he carried out the
punishment on him too and recited this verse: “certainly in that case you
would be like them”, i.e., approving of a sin is also sin. Hence the one
who did it and the one who approved of it were both punished for sin, so
they are all doomed. 

The similarity between the two does not apply in all aspects,
but they may appear to be partners in the sin, because a person is
influenced by his companion. 

Moreover there is the fear that if a person works in such
places his faith will become weak and he will lose any sense of gheerah
(protective jealousy, pride). The Shaytaan may entice him to commit 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‑Fahsha’ [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)]”

[al-Noor 24:21]

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”
[al-Talaaq 65:2-3]

 And the Prophet (peace and blessings of Allaah be upon
him) said: “Whoever gives up a thing for the sake of Allaah, Allaah will
compensate him with something better than that.” Classed as saheeh by
al-Albaani. Do not forget that no soul will ever die until it has been given
its full provision, sooner or later. 

We ask Allaah to help you to give up this job willingly and
to compensate you with something better than it, and to grant you provision
by His bounty, and to grant us and you sufficient means from that which is
permissible so that we have no need of that which is forbidden. 

And Allaah knows best.