Bukhari

Hadith Commentary:
In the narration, by Ibn Qawqal is meant Nu'man bin Malik bin Tha'laba bin Ahram bin Fihr bin Ghanam, a Companion. Qawqal was the title of his grandfather Tha'laba. He was martyred on the day of Uhud at the hands of Aban.
It is said that on that day he made this supplication: "O Allah! Let me tour Paradise before the sun sets." Allah accepted his supplication, and he was martyred before the sun had set.
"Wabar" in Arabia refers to an animal smaller than a cat, whose tail and ears are short.
"Qadoom" and "Dhan"—the words that have appeared—some have said that this is the name of a mountain near the tribe of Daws. Abu Hurayrah radi Allahu anhu was a resident of that area. Thus, Aban bin Sa'id taunted Abu Hurayrah radi Allahu anhu, likening his short stature to the wabar and calling him a shepherd of goats, thereby also admitting his own crime. However, at that time he had not yet become Muslim; later, Allah honored him with the wealth of Islam.
Hafiz sahib rahimahullah says:
"And what is meant here is the statement of Aban: 'Allah honored him at my hand and did not humiliate me at his hand.' By this he meant that Nu'man was martyred at the hand of Aban, so Allah honored him with martyrdom, and Aban was not killed in a state of disbelief, which would have led him to the Fire, and that is what is meant by humiliation. Rather, Aban lived until he repented and accepted Islam, and his Islam was before Khaybar, after Hudaybiyyah. He said this statement in the presence of the Prophet sallallahu alayhi wa sallam, and he approved it, and it is in accordance with what is contained in the chapter heading." (Fath al-Bari)
The meaning of Aban's statement here is that Allah granted him (Nu'man) the honor of martyrdom at my hand, and did not humiliate me by having me killed at his hand, which is to say that Nu'man radi Allahu anhu was martyred at the hand of Aban, so Allah honored him, and Aban did not die in disbelief, otherwise he would have gone to Hell.
Allah granted him Islam after Hudaybiyyah.
Aban made these statements in the presence of the Prophet sallallahu alayhi wa sallam, and he remained silent, thus establishing the chapter heading.
The Prophet sallallahu alayhi wa sallam did not assign a share to Abu Hurayrah radi Allahu anhu.
On this, Hafiz sahib rahimahullah says: "And it is used as evidence by the one who says that whoever arrives after the battle has ended, even if he came to assist them, is not to be included in the shares with those who were present, and this is the view of the majority." (Fath al-Bari)
That is, it is used as evidence by the one who says that a person who arrives after the battle is over, even if he came to help, is not to be included in the shares with those who were present.
This is the view of the majority.

Hadith Commentary:
➊
The name of Ibn Qutal is Nu'man bin Malik.
He was martyred at the Battle of Uhud at the hands of Aban bin Sa'id. He had supplicated in the field of Uhud: "O Allah! I wish to tour Paradise before sunset."
Allah, the Exalted, honored his supplication with acceptance, and he was martyred before the sun had set. At that time, Aban bin Sa'id was a disbeliever, but after the Battle of Uhud and before Hudaybiyyah, he embraced Islam.
➋
Imam al-Bukhari rahimahullah has established from this that both the killer and the one killed can be deserving of Paradise, as is evident from the aforementioned incident.
➌
From this hadith, it is understood that if a person repents from a sin, then all previous sins are forgiven.
After that, it is not permissible to shame him on account of that sin.
And Allah knows best.

Hadith Commentary:

The meaning of what Aban bin Sa'id radi Allahu anhu said was that if I killed Ibn Qawqal radi Allahu anhu, it was during my time of disbelief, and martyrdom brings honor in the presence of Allah, which he attained through my hands.

On the other hand, it was also Allah's favor that, in the state of disbelief, He did not allow me to be killed at his hands, which would have been a cause of my humiliation in the Hereafter, and now I am a Muslim and have faith in Allah and His Messenger sallallahu alayhi wa sallam.

Therefore, it is better not to mention such matters now.

Upon hearing this statement from Aban radi Allahu anhu, the Prophet sallallahu alayhi wa sallam remained silent.

Hadith Commentary:
Aban bin Sa'id radi Allahu anhu gave refuge to Uthman radi Allahu anhu in Makkah Mukarramah when he (Uthman radi Allahu anhu) came as the representative of the Messenger of Allah sallallahu alayhi wa sallam to Makkah at the time of the Treaty of Hudaybiyyah. At that time, Aban was a disbeliever and he accepted Islam after the Treaty of Hudaybiyyah.

Sa'id bin As relates that his father was killed at Badr, so his uncle Aban raised him, and he (Aban) was a severe enemy of the Messenger of Allah sallallahu alayhi wa sallam and used to revile him. My uncle went to the region of Syria, and when he returned, he refrained from reviling the Prophet sallallahu alayhi wa sallam. When the reason for this was asked, he said that he had met a monk in Syria who informed him of the attributes of the Messenger of Allah sallallahu alayhi wa sallam, and from that time, the truthfulness of the Prophet settled in his heart. Thus, shortly thereafter, he came to Madinah Tayyibah and accepted Islam.

He had martyred Nu'man bin Qawqal in the Battle of Uhud. The essence of Aban radi Allahu anhu's statement in this hadith is that he killed Ibn Qawqal while he himself was a disbeliever at that time, and Nu'man bin Qawqal was a Muslim, so Allah Ta'ala granted him (Nu'man) the station of martyrdom at my hands. And if Nu'man radi Allahu anhu had killed me at that time, I would have been humiliated and disgraced in both worlds and would have always been fuel for Hellfire.

In reality, both Abu Hurairah radi Allahu anhu and Aban radi Allahu anhu objected to each other and said to the Messenger of Allah sallallahu alayhi wa sallam: He should not be given a share from the spoils of war. Abu Hurairah radi Allahu anhu's position was that he is the killer of Ibn Qawqal, therefore he should absolutely not be given any share from the spoils of war, whereas Aban radi Allahu anhu said: What need do you have to descend from the mountain of Dhan and interfere in our distribution?

In any case, the Messenger of Allah sallallahu alayhi wa sallam, after consulting the Mujahideen, gave Abu Hurairah radi Allahu anhu a share from the wealth of Khaybar, but gave nothing to Aban and his companions.

(Fath al-Bari: 7/615)