Bukhari

Hadith Commentary:
That is, towards the eastern lands.
In this hadith, no specific person's name is mentioned; rather, whoever appears from that direction and calls towards misguidance and irreligion can be intended by it. It is astonishing regarding those people who have taken Imam Muhammad bin Abdul Wahhab rahimahullah to be the one intended by this tribulation.
Imam Muhammad bin Abdul Wahhab rahimahullah used to call people towards tawhid (monotheism) and adherence to the Sunnah.
In the treatise he wrote and sent to the people of Makkah, it is clearly stated that the Qur'an and authentic hadith are the criterion between us and you; act upon them.
However, in the eastern lands, Sir Syed Ahmad Khan, the leader of the modernists, and Mirza Ghulam Ahmad Qadiani can be considered as the referents of this hadith.
Our teacher, Maulana Bashiruddin Sahib Kanauji, the hadith scholar, used to say that by "the east" is meant the town of Badaun; it was from there that Fazl Rasul appeared, who spread many innovations in the world and declared the Ahl al-Hadith and the people of tawhid to be disbelievers (Wahidi).

Hadith Commentary:
The intended meaning is the east. At the time of sunrise and sunset, Shaytan places his head upon the sun so that the prostration of the sun-worshippers is directed to Shaytan.

Hadith Commentary:
The meaning of "the horn of Satan" is the edge of his head, that is, he brings his head close to the sun at the time of its rising, so that those disbelievers who prostrate to the sun are as if they are prostrating to him. And it has been said that "his horn" refers to his followers and his sect, and in some narrations, it is mentioned as "the horn of the sun."
(Commentary of Sahih Bukhari)
That is, by "the horn of Satan" is meant the edge of his head.
At the time of sunrise, he turns his head towards it so that the disbelievers who prostrate to the sun may prostrate to him.
It is as if they are prostrating to him.
It has been said that by "horn" is meant his followers, those who are worshippers of Satan.
Allamah ‘Ayni rahimahullah states that the Messenger of Allah sallallahu alayhi wa sallam pointed towards the east, towards the land of Iraq, which in reality has been a center of tribulations.

Hadith Commentary:
To the east of Madinah lie the lands of Iraq, Arabia, Iran, and other such countries.
It is from these very regions that many tribulations (fitan) have originated.
The tribulation of the Tatars also began from this direction, who devastated many Islamic lands.

Hadith Commentary:
➊
The meaning of "qarn" is strength, that is, the emergence of satanic strength will be from the east. The Messenger of Allah (sallallahu alayhi wa sallam) pointed towards the east. At that time, the people of the east were disbelievers. The Prophet (sallallahu alayhi wa sallam) foretold that tribulation would appear from that direction, and so it happened: the battles of Jamal and Siffin were fought in that direction, and then the emergence of the Khawarij occurred in the land of Iraq.

➋
The foundation of all tribulations is the martyrdom of Uthman (radi Allahu anhu), the planning of which took place in the land of Iraq. It should be noted that at the time of sunrise and sunset, Satan places his head upon the sun so that the prostration of sun-worshippers is for Satan. It is possible that "qarn al-shaytan" or "qarn al-shams" refers to this. And Allah knows best.

Hadith Commentary:
At the time of sunrise, Satan places his head upon it so that the prostration of sun-worshippers becomes directed to Satan. The scholars have written that this hadith is an indication of the corruption caused by the Turks during the era of Genghis Khan; they inflicted great destruction upon the Muslims, plundered Baghdad, and ruined the Islamic Caliphate.
(Wahidi)

Hadith Commentary:
In one narration, it is clarified that the Prophet (sallallahu alayhi wa sallam) said:
“Harshness and hard-heartedness are among the people of the lowest tents, those who call out near the tails of camels and cattle, meaning their affiliation will be with the tribes of Rabi‘ah and Mudar.”
(Sahih al-Bukhari, al-Manaqib, Hadith: 3498)
Imam al-Bukhari (rahimahullah) has alluded to this narration because its wording corresponds exactly with the chapter heading.
The scholars have said:
This hadith alludes to the corruption that occurred during the era of Genghis Khan.
They plundered the Muslims extensively, destroyed Baghdad, and not only harmed the Islamic Caliphate but brought it to an end.
Wa Allahu al-musta‘an.

Hadith Commentary:
➊
By this is meant the land of Iraq, which lies to the east of Madinah Tayyibah, and from the beginning until today, it has been a center of tribulations.

➋
This hadith is among the signs of prophethood, because the Messenger of Allah (sallallahu alayhi wa sallam) informed that the beginning of tribulations would be from the east. Thus, just as he (sallallahu alayhi wa sallam) said, so it happened, and the tribulations began from the east. We have already detailed these tribulations earlier.

➌
In this hadith, the rising is attributed to the horn. But in reality, it is the sun that rises. In fact, at the time of sunrise, the horn of Satan is also present, and for this reason, the rising is attributed to the horn instead of the sun.

Hadith Commentary: Benefits and Issues: Musa (alayhis salam) killed only one Copt by mistake, unintentionally and without deliberation, yet he was overcome with grief and sorrow over it. In contrast, these people do not feel any shame in deliberately and intentionally killing all the Muslims. They scrutinize even the smallest issues in great detail, which gives the impression that they are very pious and God-fearing. However, creating division among Muslims, inciting tribulation (fitnah), spreading propaganda against the Imams, and rebellion are their habitual practices. Similarly, Hazrat Salim rahimahullah has identified the people of Iraq as the referent of "the East." "The people of Iraq had asked about the blood of a mosquito, while they had already martyred Husayn radi Allahu anhu." This also proves that the referent of this hadith is the people of Iraq, not the designated Najdis whom the Hanafis strive to make its referent.

Explanation:
1:
The meaning is that the emergence of tribulation (fitnah) will be from the eastern direction of Madinah (i.e., Iraq).

Takhrij al-Hadith: [وأخرجه البخاري 3279، من حديث مالك به]
Jurisprudential Explanation:
➊ By "the East" is meant the region of Iraq, as is established from other ahadith.
➋ For further details, see the previous hadith: Bukhari (1525) and Muslim (1182).
➌ By "the horn of Satan" is meant a great tribulation (fitnah).
➍ The unseen matters that Allah, the Exalted, informed the Messenger of Allah (sallallahu alayhi wa sallam) of through revelation will certainly come to pass exactly as stated.
➎ Many of the signs of the Hour have yet to appear.
➏ This hadith is among the signs of prophethood.
➐ The chain of prophets was terminated forever with the true Messenger of Allah, the Noble Prophet (sallallahu alayhi wa sallam).
➑ Many tribulations occurred in Iraq, such as the martyrdom of Husayn (radi Allahu anhu). See [التمهيد 17/12]
That is, the instigators of tribulation and the oppressors martyred our master Husayn (radi Allahu anhu), which was a great injustice. The battle that took place between the oppressor and the oppressed in Iraq, at Karbala (Karb wa Bala’), is a calamity whose consequences the Ummah continues to bear to this day.