Muslim

Hadith Commentary:
Allamah Ibn Hajar rahimahullah says regarding Hasan ibn Ishaq, the teacher of Imam Bukhari:
"He was among the companions (students) of Ibn al-Mubarak, and he passed away in the year 241 AH. He has no narration in Sahih Bukhari except for this hadith." (Fath)
That is, he was among the students of Abdullah ibn al-Mubarak.
He passed away in 241 AH.
In Sahih Bukhari, only this one hadith is narrated from him.

Hadith Commentary:
➊
Siffin is the name of a place between Iraq and Syria where the battle took place between Amir Muawiyah (radi Allahu anhu) and Ali (radi Allahu anhu).

➋
Sahl bin Hunayf (radi Allahu anhu) did not participate in this battle, so people considered this action as a shortcoming. At that time, he said:
Do not be proud of your own opinion.
You people are fighting your Muslim brothers based on your own reasoning.
Our condition at the time of the Treaty of Hudaybiyyah was just like yours is now, but Allah, the Exalted, restrained us from fighting at that time, and there was goodness and blessing in it.
By participating in the battle, you have made a mistake.
There is some detail regarding this in Musnad Ahmad: When, in the Battle of Siffin, the people of Syria began to be killed, they took refuge behind a sand dune.
Upon the suggestion of Amr bin al-As (radi Allahu anhu), it was announced to make the Book of Allah the arbiter. The Khawarij said that we should go behind the sand dune and wipe them out.
On this occasion, Sahl bin Hunayf (radi Allahu anhu) said: O people! Reconsider your opinion.
It is more expedient to make peace rather than slaughtering each other.
(Musnad Ahmad: 3/488)

➌
Imam Bukhari (rahimahullah) wants to establish from this hadith that Sahl bin Hunayf (radi Allahu anhu) was present at the Treaty of Hudaybiyyah and that he participated in the Bay‘at al-Ridwan.
And Allah knows best.

Hadith Commentary:
Hazrat Sahl bin Hunaif radi Allahu anhu did not participate on either side in the battle.
That is why both groups were blaming him.
He replied to this by saying that the Messenger of Allah sallallahu alayhi wa sallam did not command us to fight against Muslims.
It is your own mistake that you are killing your own brothers with your own swords.
Many other Companions also did not participate in the dispute between Hazrat Muawiyah radi Allahu anhu and Hazrat Ali radi Allahu anhu.
The meaning of Hazrat Sahl radi Allahu anhu was that when the Prophet sallallahu alayhi wa sallam did not hasten to fight against the disbelievers and made peace with them, then why have you become so eager to fight against Muslims?
Think carefully whether this war is permissible or not.
And what will be its outcome?
When the Battle of Siffin took place, all the disbelievers of the world, upon hearing this news, celebrated that now the strength of the Muslims would be spent among themselves.
We will all be completely safe.
Even today, the situation is such that there are so many political and religious internal conflicts among Muslims that today’s enemies of Islam are rejoicing at the sight of it.
If the condition of the Muslims had not deteriorated to this extent, their first qiblah would not have fallen into the hands of the accursed nation, the Jews.
The civil war among the Arab Muslim nations has shown the Ummah this evil day, that today the Jews are dominating over the Muslims.
The relevance of the hadith of Sahl radi Allahu anhu to the chapter is as follows: when the Quraysh broke the treaty, Allah punished them and made the Muslims victorious over them.
What Sahl bin Hunaif radi Allahu anhu said at the time of the Battle of Siffin meant that at the time of the Treaty of Hudaybiyyah, the Quraysh greatly insulted the Muslims, yet the Prophet sallallahu alayhi wa sallam did not consider it appropriate to fight them, and we remained obedient to your command; similarly, the Prophet sallallahu alayhi wa sallam has forbidden raising hands against Muslims.
How can I kill Muslims? This is what Sahl radi Allahu anhu said when people reproached him for not fighting at Siffin.
Siffin was a village on the banks of the Euphrates River,
where the battle between Hazrat Ali and Muawiyah radi Allahu anhuma took place.

Hadith Commentary:
➊
Siffin is a place on the bank of the Euphrates River, west of Raqqah, where a battle took place between Muawiyah (radi Allahu anhu) and Ali (radi Allahu anhu).
In this battle, Sahl bin Hunaif (radi Allahu anhu) was in the army of Ali (radi Allahu anhu), but he was not practically participating in the fighting, so his companions were accusing him of lack of interest.
At that time, he addressed the people with an admonition, saying:
The Messenger of Allah (sallallahu alayhi wa sallam) did not command us to fight.
It is your mistake that you are bent on killing your own brothers with your swords.
When the Messenger of Allah (sallallahu alayhi wa sallam) did not hasten to fight the disbelievers at the time of the Treaty of Hudaybiyyah and made peace with them, then why are you so eager to fight the Muslims? Think carefully, is this war permissible or not? What will be its outcome?

➋
There is no specific heading for the aforementioned ahadith; rather, their heading is related to the previous context, that when the Quraysh broke the covenant, Allah punished them and made the Muslims victorious over them.
Alas, the condition of Muslims today is pitiable.
The Muslims of the early generations would draw their swords to crush tribulations, but we Muslims today brandish weapons to promote tribulations.
Today, the enemies of Islam are rejoicing at the current situation.
Because of the mutual fighting and civil wars among Muslims, the Jews have occupied the First Qiblah, and they are riding on the shoulders of the Muslims and making them do as they please.
Inna lillahi wa inna ilayhi raji'un.

Benefit:
First, the turmoil of the first group arose, then that of the people of Sham, and then the turmoil of the Khawarij occurred, and the difficulties continued to increase.