Bukhari

Hadith Commentary:
(1)
According to this hadith, pursuing someone in order to shed innocent blood is an extremely detestable act, while actually spilling blood is an even graver crime. In another hadith, it is stated that the most rebellious person in the sight of Allah is the one who kills someone other than the killer, or who, after accepting Islam, demands blood for a killing that occurred in the pre-Islamic era of ignorance. (Al-Mu'jam al-Kabir by al-Tabarani: 191/22)

(2)
The context of this hadith's revelation is described as follows: On the occasion of the conquest of Makkah, a person was killed in Muzdalifah. The Messenger of Allah (sallallahu alayhi wa sallam) said: "I do not know anyone more rebellious in the sight of Allah than three types of people: one who kills someone in the Haram (sanctuary), the second who kills someone other than the killer, and the third who kills someone due to enmity from the era of ignorance." (Fath al-Bari: 262/12) From this hadith, it is understood that pursuing someone to take retribution for blood is not a crime, because he does so for rightful blood (qisas).

Fiqh al-Hadith
➊ To desecrate the Haram (Makkah or Madinah) is called «الحاد فى الحرم», and similarly, irreligion, disbelief, and renouncing the religion are also referred to as ilhad. See: [القاموس الوحيد ص 1457]
➋ The virtue of the two Harams is also made clear from this hadith.
➌ Some scholars have said that even the intention of committing evil in the Haram will incur punishment, whereas outside the Haram, there is no punishment or accountability merely for the intention of evil.
➍ Sayyiduna Abdullah ibn Mas'ud radi Allahu anhu said:
“If a person is (far away) in Aden and intends ilhad in the Haram, Allah Ta'ala will subject him to a painful punishment.” [مسند حمد 1؍428 ح4071 وسنده حسن، وصححه الحاكم 2؍388 ووافقه الذهبي]
➎ Among the ways of Jahiliyyah, disbelief, polytheism, and innovation are all forbidden acts. This hadith establishes the condemnation of innovation (bid'ah) and the affirmation of the Sunnah.
In Mir'at al-Mafatih, wailing over the dead in the manner of Jahiliyyah, gambling, indecency, and the professions of astrologers, etc., have been counted among the ways of Jahiliyyah. [ج 1 ص 238]
➏ In the religion of Islam, shedding anyone’s blood unjustly is forbidden.

Takhrij:
«أخرجه ابن حبان (الموارد)، حديث:1699، وللحديث شواهد عند البخاري، الديات، حديث:6882، (من حديث ابن عباس) وغيره.»©Explanation:
➊ In this hadith, three types of rebellious people against Allah Almighty are mentioned.
Among them is the unfortunate one who commits unlawful killing in the Sacred City (Balad Amin), that is, Makkah al-Mukarramah.
Killing is, in itself, a very grave crime, but to commit murder in the Two Sacred Sanctuaries (Haramayn Sharifayn) is the gravest of crimes.
From this, it is understood that the severity of a crime varies according to the place and location.
It is probably for this reason that Imam Shafi‘i rahimahullah has said: Whoever commits accidental killing (qatl khata) in the Haram, the blood money (diyah) imposed upon him should be severe.
➋ The second is the person who, instead of the actual killer, kills someone else in retaliation.
Retribution from the killer is the responsibility of the government, but the one who, in the heat of revenge, kills a relative of the killer, is guilty of a double crime.
➌ And the third is the person who takes revenge for something from the time of ignorance (Jahiliyyah) from a Muslim; he too is extremely rebellious in the sight of Allah Almighty.