Nasai

(1) "Coats of mail or armors of iron." Armor can also be made of leather, so iron is specified here in order to give greater emphasis in the following example.

(2) "Upon their chests." In any case, armor is for the chest. Here, the chest is specifically mentioned because the human heart—which is related to generosity and miserliness—is located in the chest. In this example, the armor refers to the grip of the self (nafs) that it keeps over the soul, which prevents the manifestation of spiritual perfections.

(3) "It opens up." That is, the generous person's heart loosens this grip to such an extent that the effect of generosity becomes apparent throughout his entire body, and even his hands open up in generosity. Erasing the traces of footsteps refers to erasing his mistakes. Or, it means that just as this armor covers his entire body, likewise, on the Day of Resurrection, Allah, the Exalted, will conceal his faults.

(4) "It contracts." That is, his heart becomes constricted and he does not find the courage to give charity, to the extent that giving charity becomes like strangling himself. Just as the armor contracts up to his neck, similarly, his heart becomes constricted and he is not granted the ability to give charity.

Hadith Commentary:

By "jabbatān," two shirts are meant, and by "jannatān," two coats of armor. By merely pointing towards his collar, the purpose of the chapter is fulfilled, which is that the collar of the Prophet's shirt was upon his chest.

Hadith Commentary:
(1)
According to this hadith, the example of the one who spends (in charity) is like that of a person who has put on a coat of mail (armor), and it becomes loose upon him until it covers his entire body and reaches down to his toes. The example of the miser is like that of a person whose hand is clinging to his neck, and his coat of mail is so tight that his hand cannot come out, and the armor does not loosen; rather, each ring of it remains fixed in its place. The Messenger of Allah (sallallahu alayhi wa sallam) pointed towards his collar, which was near his chest in his shirt.

(2)
Imam Bukhari (rahimahullah) has established from this that the collar is located near the chest. Hazrat Qarah (radi Allahu anhu) says that I, along with a group from the tribe of Muzaynah, presented ourselves before the Messenger of Allah (sallallahu alayhi wa sallam). I saw that the buttons of the Messenger of Allah’s (sallallahu alayhi wa sallam) shirt were open. I put my hand into his collar and touched the Seal of Prophethood. (Sunan Abi Dawud, Kitab al-Libas, Hadith: 4082) From this hadith as well, it is understood that the collar of the Prophet’s (sallallahu alayhi wa sallam) shirt was near his chest.

(3)
It should be clear that leaving the buttons open, if done out of humility and modesty, is a cause of reward. However, among us, mischievous youths keep their collars open, so it is necessary to avoid resembling them, because doing so is considered a sign of arrogance among them.

Hadith Commentary:
This hadith has already been mentioned in the Book of Zakat.
The meaning is that the generous person's heart becomes happy and expansive by giving zakat and charity, whereas the miser, firstly, does not give zakat at all, and secondly, even if he gives something under compulsion or force, he does so with a constricted and distressed heart. The tightening of the rings of his armor is an expression of this very state.
There are many verses and hadiths regarding the condemnation of miserliness. A believing man becomes so happy by giving zakat and spending for Allah that it is as if his armor has expanded and covered his entire body; his heart becomes even more expansive than the expansion of his armor.
May Allah grant every Muslim this quality, ameen.
Since this hadith mentions armor, Imam Bukhari rahimahullah has brought it here and affirmed the reality of armor.

Hadith Commentary:
According to this hadith, a believing man becomes so pleased upon giving zakat (obligatory charity) that it is as if his coat of mail (zirah) has expanded and covered his entire body.
His heart becomes even more expansive than the expansion of his coat of mail, since the mention in this hadith was of the coat of mail.
Therefore, Imam Bukhari rahimahullah narrated it here to affirm the existence of the coat of mail.
And Allah knows best.

Hadith Commentary: Benefits and Issues: When a generous person intends and resolves to give charity (sadaqah), spaciousness and courage are created in his heart, and he spends open-heartedly and with magnanimity. His charity flourishes and wipes out his sins. On the other hand, when a miserly and stingy person wishes to give charity, his heart becomes constricted and his hands shrink back. He does not find the courage or resolve to spend, and his wealth does not become a source of goodness or blessing for him.

Hadith Footnote:

Benefits and Issues:
The correct parable of the generous and the miser has been mentioned in the following narrations; in this hadith, there has been advancement and delay and alteration. In place of (مَثَلُ الْمُنْفِقِ وَالْمُتَصَدِّقِ) "the example of the spender and the giver of charity," it should be (مَثَلُ الْبَخِيلِ وَالْمُنْفِقِ) "the example of the miser and the spender." In place of (كَمَثَلِ رَجُل) "like a man," it should be (كَمَثَلِ رَجُلَيْنِ) "like two men." In place of (جبتان او جَنَّتَانِ) "two coats of armor or two armors," it is جَنَّتَانِ "two armors." (تُجِنُّ بَنَانَهُ ، وَتَعْفُو أَثَرَهُ) "it covers his fingertips and erases its trace" pertains to the giver of charity, not to the miser, and (يوسعها فلا تتسع) "he tries to widen it but it does not widen" pertains to the miser.

When a generous person intends to give charity (sadaqah), his heart becomes expansive, his hands open up, and all obstacles are removed. And if a miserly person intends to give charity, his heart becomes even more constricted, as if his hands are tied. He becomes helpless like a person bound in chains and is unable to give charity. May Allah protect us from this.

Explanation of the Hadith:
In this hadith, the examples of the miser and the one who gives charity are described. The coat of mail (armor) of the generous person becomes so wide that his fingers are concealed within it, and it hangs so low as if it were a very long garment; when the person walks, it drags on the ground and erases the footprints, meaning the heart of the generous person becomes happy and expansive by spending money. The coat of mail of the miser, on the other hand, begins to cut into his body from the very first stage, and he is not granted the ability to be generous. His hands remain imprisoned within the coat of mail. [ارشاد الساري : 38/3]

Imam Baghawi rahimahullah says: "When the generous person intends to spend in the way of Allah, his chest becomes expansive for this act, and his hands also agree in this matter, and he spends with an open hand, not sparingly. The chest of the miser becomes constricted, and his hands are reluctant to spend in acts of goodness." [شرح السنة للبغوي : 159/6]