Should he shun his colleague at work who does haraam things?

Question

Praise be to Allah.

Shunning that may occur between two Muslims because of a
dispute is of two types:

1 – Shunning someone because of ego or worldly issues.

2 –Shunning because of the rights of Allaah, because the
person being shunned has fallen into innovation (bid’ah) or sin.

The ruling on the first type is that it is not prescribed in
Islam, rather it is forbidden.

It was narrated from Anas ibn Maalik that the Messenger of
Allaah (peace and blessings of Allaah be upon him) said: “Do not hate
one another, do not envy one another, do not turn away from one another. Be,
O slaves of Allaah, brothers. It is not permissible for a Muslim to forsake
his brother for more than three days.”

Narrated by al-Bukhaari (5726) and Muslim (2559).

It is not permissible for this kind of shunning to go on for
more than three days because of what it says in this hadeeth.

The ruling on the second type is that it is a kind of
shunning that is prescribed in Islam, and there is evidence for that in the
Sunnah. This was done by the Sahaabah and by the imams of Islam after them,
but it is subject to conditions and guidelines that have been discussed by
the scholars.

The Prophet (peace and blessings of Allaah be upon him)
shunned the three men who stayed behind from the campaign to Tabook with no
excuse. The lengthy hadeeth about their story is narrated in al-Saheehayn
from Ka’b ibn Maalik (may Allaah be pleased with him), who was one of the
three.

Al-Haafiz Ibn Hajar (may Allaah have mercy on him) said,
discussing the lessons learned from this hadeeth:

(One of the lessons we learn) is not saying salaams to one
who commits sin, and that it is permissible to shun him for more than three
days. The prohibition on shunning someone for more than three days is to be
understood as referring to situations where the reason for shunning is not
something prescribed in Islam.

(Another lesson we learn) is that the obligation to return
salaams is waived in the case of one who is greeted by the person who is
being shunned, because if it were obligatory, Ka’b would not have wondered
whether he (the Prophet (peace and blessings of Allaah be upon him))
moved his lips in returning the greeting.

Fath al-Baari (8/124).

It is clear to us from the context of the hadeeth – which we
will not quote here due to its length – that one of the rulings on the kind
of shunning that is prescribed in Islam is that is it permissible not to
give or return salaams to the one who is sinning – and even more so in the
case of one who is introducing innovation – and that there is no time limit
on shunning him, rather that may last until he repents or until the one who
is shunning him thinks that the purpose has been served – as we shall see
below. Hence you can see that there is nothing Islamically wrong with your
not shaking hands with that sinner and not greeting him. To make the matter
more certain:

Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him)
said:

If a person is known to openly fail to do obligatory duties
or to do haraam things, then he deserves to be shunned and should not be
greeted with salaams, as a rebuke to him, until he repents.

Majmoo’ al-Fataawa (23/252).

But it is essential to note that shunning of sinners and
innovators has only been prescribed for important reasons, such as shunning
him in order to discipline him so that he will give up his sin and
innovation, and to warn others against falling into sin and innovation. If
shunning has no effect on the sinner or only makes him more stubborn, then
there is no point in shunning him, because of the bad consequences to which
that may lead for the one who is shunned, or because it will not serve the
purpose for which shunning was prescribed. In that case softening the heart
of the sinner will be more effective than shunning him.

Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him)
said:

Shunning varies according to how strong or weak, and how few
or how numerous the people who are doing the shunning are. The purpose is to
rebuke and discipline the person being shunned and to deter the masses from
doing likewise.

If the purpose is more likely be to achieved by shunning, and
it will weaken and reduce the evil, then it is prescribed, but if the person
being shunned and others will not be deterred by that, rather the evil will
increase, and the person doing the shunning is weak and the bad consequences
will outweigh the good, then shunning is not prescribed, rather softening
the hearts of some people is more effective than shunning.

But in some cases shunning is more effective than softening
the hearts. Hence the Prophet (peace and blessings of Allaah be upon
him) sought to soften the hearts of some people and shunned others, and the
three who stayed behind (from Tabook) were better than most of those whose
hearts were to be softened, because they were leaders who held positions of
influence among their tribes. So the interests of Islam dictated that the
hearts of the leaders be softened, whereas the three who were shunned were
believers and there were many other believers besides them. So shunning them
was supporting Islam and was a means of purifying them of their sins.
Similarly what is prescribed with regard to the enemy is to fight them
sometimes, and to seek truces with them sometimes, and to take the jizyah
sometimes, according to circumstances and what is in the ummah’s best
interests.

Majmoo’ al-Fataawa (28/206).

Shaykh Muhammad ibn Saalih al-‘Uthaymeen (may Allaah have
mercy on him) was asked:

What is the guideline on shunning a sinner who does not
commit sin openly in front of people, if there is an interest to be served
by shunning him?

He replied:

The guideline is that if shunning a sinner will serve a
purpose such as deterring him from his sin, then he should be shunned. But
if it will serve no purpose, then shunning him is haraam, because the sinner
is still a Muslim, no matter what major sin he may commit, except kufr if
that is the case. This is well known. The Prophet (peace and blessings
of Allaah be upon him) said: “It is not permissible for a Muslim to shun his
fellow-Muslim for more than three (days), each of them turning away if they
meet. The better of them is the one who greets the other first.” So you
should not shun him. And there are some sinners who, if they are shunned,
will increase in sin and hate you as well, and will not accept any advice
from you. But if shunning him will be of benefit, such as if he is one of
your children or brothers, and he respects you, and shunning him will serve
as a rebuke, then in the case you may shun him so that he will be rebuked.
Then if you shun him but that does not work as a rebuke, then you should
resume contact with him and greet him with salaam, and do not forget to
advise him.

Liqaa’aat al-Baab il-Maftoohah
(231/question no. 9).

If you think that not greeting him with salaam will have an
effect on him and will work as a rebuke for his sins, then carry on shunning
him and stop greeting him with salaam or responding if he greets you. But if
you think that this is of no benefit, then remember that seeking to soften
his heart with gifts, smiling at him and speaking kindly to him may be more
effective than shunning him, so do that. If he refuses that from you, and
does not respond to you, then there is no sin on you and you are not to
blame for that.

In Musnad al-Imam Ahmad (15823) it is narrated that
Hishaam ibn ‘Aamir said: I heard the Messenger of Allaah (peace and
blessings of Allaah be upon him) say: “It is not permissible for a Muslim to
shun a Muslim for more than three days. If they forsake one another for more
than three days then they are deviating from the truth so long as they are
forsaking one another. If one of them attempts reconciliation first, that
will be an expiation for him. If he greets him with salaam and he does not
respond or return his salaam, then the angels will respond to him and the
shaytaan will respond to the other one, and if they die whilst forsaking one
another they will never meet in Paradise!”

Classed as saheeh by al-Albaani in al-Saheehah, 1246.

We ask Allaah to decree reward for us and you, and to guide
us and you to what which He loves and which pleases Him.

And Allaah knows best.