Bukhari

Hadith Commentary:
From this hadith, the Imam (rahimahullah) has deduced that having burning coals of fire in front of oneself during prayer does not cause any harm.

Hadith Commentary:
1.
Imam Bukhari rahimahullah has narrated this hadith from Ibn Abbas radi Allahu anhu here in a very concise manner.
In detail, it is reported that the Messenger of Allah sallallahu alayhi wa sallam suddenly stepped back during the prayer, then moved forward.
Upon inquiry after the prayer, he explained that during the prayer, Paradise was brought before him, and he advanced to pluck a bunch of its grapes.
Then Hell was shown to him, and upon seeing its terrifying scene, he stepped back (Sahih al-Bukhari, al-Kusuf, Hadith: 1052).
Imam Bukhari rahimahullah has established with this chapter heading that if there is fire in front of the one praying, and the intention of the worshipper is solely to pray for Allah, then there is no harm in it.
In reality, Bukhari has to use indications to establish such ijtihadi (jurisprudential) issues, because there is no explicit text in the books of hadith that the Messenger of Allah sallallahu alayhi wa sallam ever prayed with fire intentionally placed in front of him in normal circumstances.
Imam Bukhari rahimahullah, through this chapter heading, wants to refute the position of Imam Ibn Sirin rahimahullah, whose view is that it is disliked (makruh) to pray facing an oven (tanur).
(Fath al-Bari: 1/684)
Hafiz Ibn Hajar rahimahullah has clarified Imam Bukhari’s position from another angle.
He states that Imam Bukhari may wish to clarify, through the presented narrations, the distinction that:
If there is fire between the worshipper and his qiblah, and he has the ability to remove it or move away from it, then in such circumstances, praying is disliked (makruh). But if he is compelled to keep such a fire and does not have the ability to remove it, then in such circumstances, praying is permissible.
As is narrated regarding Ibn Abbas radi Allahu anhu, that he would not pray in a church in which there were images on the front wall, but in such circumstances, he would choose to pray outside in the rain.
2.
Some individuals have also objected that in this hadith, only the seeing of the fire is mentioned, but that the Prophet sallallahu alayhi wa sallam saw this scene in the front wall is not mentioned in the hadith.
It is possible that he saw the fire on the right or left side, so deducing non-dislike (adam karaha) from this narration is questionable.
However, this objection holds no weight, because in the hadith of Anas, it is explicitly stated that during the prayer, that fire was presented to him.
Even more explicit is the hadith of Ibn Abbas radi Allahu anhu.
In it, after the prayer, the people said:
O Messenger of Allah sallallahu alayhi wa sallam! We saw you advancing during the prayer as if you were reaching for something, then suddenly we saw you stepping back, so you said that Paradise and Hell were brought before me.
From this, it is understood that the fire was in front of him, and in light of these narrations, the distinction of whether the fire is near or far from the worshipper is also not correct.
(Fath al-Bari: 1/684)
It should be clear that the fire itself was brought to you.
It is a far-fetched possibility that the fire remained in its place and only the veils in between were removed.
And Allah knows best.
3.
From this hadith, it is understood that there is no harm in installing a gas heater in the mosque, even if it is in the direction of the qiblah. However, caution demands that they be installed on the right, left, or rear wall, so that if placed in front, they do not become a cause of distraction for the worshipper.