The hadith “Woe to ‘Ammaar; he will be killed by the transgressing group; he will be calling them to Paradise and they will be calling him to Hell,” and refutation of the specious argument which quotes it to cast aspersions upon Mu‘aawiyah

Firstly: 

What is required is to think positively of those whom Allah chose to
accompany His Prophet (blessings and peace of Allah be upon him): for they
are the best companions of the best Prophet, and it is not permissible to
say anything of them but the highest words of praise; if anyone criticises
them, then this gives rise to suspicion about the sincerity of his religious
commitment. 

Abu Zar‘ah ar-Raazi (may Allah have mercy on him) said: If you see a man
criticising any of the Companions of the Messenger of Allah (blessings and
peace of Allah be upon him), then know that he is a heretic. That is because
in our view, the Messenger of Allah (blessings and peace of Allah be upon
him) is true, and the Qur’an is true. No one transmitted this Qur’an and the
Sunnah to us except the Companions of the Messenger of Allah (blessings and
peace of Allah be upon him). They only seek to undermine our witnesses (to
the authenticity of the texts) in order to declare the Qur’an and Sunnah
false, but these people are more deserving of criticism, for they are
heretics.

End quote from al-Kifaayah fi ‘Ilm ar-Riwaayah by al-Khateeb
al-Baghdadi (p. 49). 

See also the answer to question no.
187689 

Secondly: 

The Companions of the Prophet (blessings and peace of Allah be upon him)
fought one another ,and each party had a reason to fight, which was based on
their own understanding of the texts and on their own ijtihaad, whereby each
party believed it was in the right. Hence when it became clear to some of
them that they were mistaken, they regretted going out and fighting, and
regret is repentance, and repentance erases what comes before it, especially
in the case of the noblest of mankind, and the highest in status and most
respected of them after the Prophets and Messengers of Allah. 

Whoever examines this matter properly will realise that this fighting was
caused by those who sought to spread discord by spreading rumours and false
ideas.  

Many of the Sahaabah (may Allah be pleased with them) went out during this
fighting seeking to reconcile between the people. Fighting was the most
hateful thing to them, but the decree of Allah inevitably came to pass. 

Thirdly: 

Al-Bukhaari (447) narrated from Abu Sa ‘eed al-Khudri, in the report about
the building of the mosque (in Madinah), that he said: We would carry one
brick at a time, but  ‘Ammaar would carry two bricks at a time. The Prophet
(blessings and peace of Allah be upon him) saw him and brushed the dust from
him, saying: “Woe to ‘Ammaar; he will be killed by the transgressing group;
he will be calling them to Paradise and they will be calling him to Hell”.
‘Ammaar said: I seek refuge with Allah from tribulation. 

What is meant by calling to Paradise in this hadith is calling to the means
of attaining it, which is obedience to the caliph (Ameer al-Mu’mineen), and
what is meant by calling to Hell is calling to that which leads to it, which
is opposing the caliph and rebelling against him. 

But whoever did that on the basis of ijtihaad and valid interpretation is
excused. 

Al-Haafiz Ibn Katheer (may Allah have mercy on him) said: 

This hadith is one of the signs of Prophethood, as the Prophet (blessings
and peace of Allah be upon him) foretold to ‘Ammaar that he would be killed
by the transgressing group, and he was killed by the people of ash-Shaam
(greater Syria) in the battle of Siffeen, when ‘Ammaar was with ‘Ali  and
the people of Iraq, as will be explained in detail below. ‘Ali had more
right to rulership than Mu‘aawiyah did. 

The fact that the companions of Mu‘aawiyah are described as transgressors
does not imply that they were disbelievers, as the ignorant followers of the
misguided sects, such as the Shi‘ah  and others, try to claim. That is
because their decision to fight was based on their own ijtihaad and
interpretation of the texts, and not everyone who engages in ijtihaad gets
its right; rather the one who gets it right will have a twofold reward and
the one who gets it wrong will have a single reward. 

Those who added to this hadith after the phrase “you will be killed by the
transgressing group” the words “Allah will not grant them my intercession on
the Day of Resurrection” fabricated this additional material, falsely
attributing it to the Messenger of Allah (blessings and peace of Allah be
upon him), for he did not say it, as it was not narrated via any acceptable
chain of narration. And Allah knows best. 

With regard to the words “he will be calling them to Paradise and they will
be calling him to Hell”, ‘Ammaar and his companions were calling the people
of greater Syria to reconciliation and unity, whereas the people of greater
Syria wanted to seize power from one who was more entitled to it, and they
wanted the people to be divided, with each part of the Muslim lands having
its own ruler, which would lead to disunity and division of the ummah, for
this was the implication of their view and the consequences to which it
would lead, even if they did not intend that. And Allah knows best.

End quote from al-Bidaayah wa’n-Nihaayah (4/538) 

Al-Haafiz Ibn Hajar (may Allah have mercy on him) said: 

If
it is said: “He was killed at Siffeen, when he was with ‘Ali, and those who
killed him were with Mu‘aawiyah, with whom were some of the Sahaabah, so how
can it be said that they were calling to Hell?”

The answer to that is that they thought that they were calling to Paradise,
and their action was based on ijtihaad, so there is no blame on them for
following what they thought was best. What is meant by calling people to
Paradise is calling them to that which leads to it, which is obeying the
ruler. This was the stance of ‘Ammaar, who was calling them to obey ‘Ali,
who was the ruler whom it was obligatory to obey at that time, whereas they
(Mu‘aawiyah and his followers) were calling people to something other than
that, but they are excused for the wrong conclusion they reached, which was
based on misinterpretation of the texts. 

End quote from Fath al-Baari (1/542). See also: Majmoo‘ Fataawa
Shaykh al-Islam (4/437) 

So
it is essential to differentiate between the one who tries to work it out
but reaches a wrong conclusion, and the one who deliberately causes mischief
and turmoil. 

Allah, may He be exalted, says (interpretation of the meaning):

“And if two
parties or groups among the believers fall to fighting, then make peace
between them both, but if one of them rebels against the other, then fight
you (all) against the one that which rebels till it complies with the
Command of Allah; then if it complies, then make reconciliation between them
justly, and be equitable. Verily! Allah loves those who are equitable.

The believers are nothing else than brothers (in Islamic
religion). So make reconciliation between your brothers, and fear Allah,
that you may receive mercy”

[al-Hujuraat 49:9-10]. 

This indicates that it is possible for fighting to occur among the
believers, without that meaning that one of the groups is regarded as no
longer being believers because of their fighting the other group. Then
Allah, may He be exalted, says: “The
believers are nothing else than brothers (in Islamic religion). So make
reconciliation between your brothers”
[al-Hujuraat 49:9-10]. 

So
Allah described them as being brothers, despite their fighting, and He
commanded the Muslims to reconcile between them. 

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

Allah, may He be glorified and exalted, explains that despite their fighting
and transgression against one another, they are still believers and
brothers, and He enjoined reconciling between them. But if one of them
transgresses after that, then the transgressing group is to be fought, but
He did not enjoin fighting from the outset. 

The Prophet (blessings and peace of Allah be upon him) stated that the
groups that would pass out of the faith [the Khawaarij or Khaarijis] would
be killed by the closer of the two groups to the truth, and ‘Ali ibn Abi
Taalib and those who were with him were the ones who fought
them.                                     

The words of the Prophet (blessings and peace of Allah be upon him) indicate
that they were closer to the truth than Mu‘aawiyah and those who were with
him, although both groups were believers.

End quote from Majmoo‘ al-Fataawa (25/305-306) 

It
was narrated that Abu Sa‘eed al-Khudri said: The Messenger of Allah
(blessings and peace of Allah be upon him) said: “A group will secede from
my ummah at a time of division among the Muslims, and they will be killed by
the group that is closer to the truth.”

Narrated by Muslim (1064). 

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

This saheeh hadeeth indicates that both of the groups who engaged in
fighting – ‘Ali and his companions, and Mu‘aawiyah and his companions – were
following the truth, and that ‘Ali and his companions were closer to the
truth than Mu‘aawiyah and his companions.

End quote from Majmoo‘ al-Fataawa (4/467). See also: Majmoo‘ al-Fataawa
(4/437-438). 

For more information, see the answers to questions no.
147974 and 140984

To
sum up: 

The words “they will be calling him to Hell” do not imply disbelief – Allah
forbid. The one who says that is only highlighting his extreme ignorance.
Rather these hadiths come under the heading of the hadiths of warning, like
those hadiths which say that the one who consumes riba will be in the fire,
and the one who consumes the orphan’s wealth will be in the fire, and other
hadiths that contain warnings; they do not necessarily imply that the person
who does that is a disbeliever, although they do indicate that his deed is
haraam and is in fact a major sin. 

In
fact some of the scholars interpreted the words “they will be calling him to
Hell” as referring to the Khawaarij (Kharijites). 

Ibn Battaal (may Allah have mercy on him) said: 

The words “he will be calling them to Paradise and they will be calling him
to Hell” can only be correctly applied to the Khawaarij to whom ‘Ali sent
‘Ammaar to call them to join the jamaa‘ah (main body of the Muslims); they
cannot be correctly applied to any of the Sahaabah, because it is not
possible for any of the Muslims to interpret any of their actions except in
the best manner, because they were the companions of the Messenger of Allah
(blessings and peace of Allah be upon him), whom Allah praised and testified
to their virtue, and said (interpretation of the meaning):
“You 
are the best of peoples ever raised up for mankind”
[Aal ‘Imraan 3:110]. 

The commentators said: This refers to the Companions of the Messenger of
Allah. It is narrated in a saheeh report that ‘Ali sent ‘Ammaar to the
Khawaarij to call them to join the jamaa‘ah (main body of the Muslims), with
whom there is protection from error. 

End quote from Sharh Saheeh al-Bukhaari (2/98-99) 

For more information, please see the answer to question no.
171167

And Allah knows best.