Bukhari

Hadith Commentary:

The narrator’s assumption is not correct that Abu Hurairah radi Allahu anhu forgot the hadith and therefore denied it; rather, the reason for his denial was that the student presented the hadith in a manner suggesting a contradiction. He became displeased at this because these two ahadith pertain to two separate subjects, and there is no question of contradiction between them.

Some people have said that the ruling in the hadith—to keep healthy animals separate from sick animals—exists precisely to prevent the misconception that commonly arises in the minds of ordinary people regarding such matters. If, by keeping them together, the healthy animals also become sick, the suspicion may arise that all of this happened because of the sick animal. The Shari‘ah has refuted such notions.

Hadith Commentary:
(1)
The opinion of the narrator Abu Salamah is questionable, namely that Abu Hurairah radi Allahu anhu denied the hadith due to forgetfulness. Rather, the reason for his denial was that the hadith was being presented in a manner of contradiction. Abu Hurairah radi Allahu anhu became displeased at this, so he expressed his displeasure in the Abyssinian language. In reality, there is no contradiction between the ahadith; rather, both pertain to separate subjects. The purpose of the first hadith is to negate the ignorant belief that disease is naturally transmitted from one to another. This does not negate the possibility of harm occurring by the power of Allah Ta'ala. In the second hadith, the prohibition of bringing a sick camel among healthy camels is due to the fact that people of little knowledge might fall into baseless superstitions, thinking that the healthy camels became sick because of the sick camel, thus affirming contagion (ʿadwā), whereas the hadith prohibits this belief.

(2)
It is also possible that Abu Hurairah radi Allahu anhu denied it due to forgetfulness, as Abu Salamah has stated. There is nothing surprising in this, for forgetfulness is a human trait. However, it is mentioned in the hadith that the Messenger of Allah sallallahu alayhi wa sallam made supplication for Abu Hurairah radi Allahu anhu, so Abu Hurairah radi Allahu anhu said: After that, I have not forgotten any hadith. (Sahih al-Bukhari, Kitab al-ʿIlm, Hadith: 119)

(3)
In any case, Imam al-Bukhari rahimahullah, through this hadith, has negated the ignorant belief that after death, a poisonous worm emerges from a person’s skull and continuously calls out: "Give me to drink, give me to drink." When retribution for the murdered person is taken, it disappears. This belief has no basis. Some people have said: Among the superstitions of the Arabs was that if someone was killed and retribution was not taken, an owl would emerge from the skull of the dead person, circling above it and calling out: "Thirst, thirst." If retribution for the murdered person was taken, it would become satisfied. Based on this superstition, those people would insist on taking retribution by any means possible. The Messenger of Allah sallallahu alayhi wa sallam refuted this superstition. And Allah knows best.