Bukhari

Hadith Commentary:
Most scholars have said that by the pronouns in “her arm was the longest” and “she was,” what is meant is Zaynab (radi Allahu anha), but her name is not mentioned in this narration.
Because it is agreed upon that after the passing of the Prophet (sallallahu alayhi wa sallam), the first among his wives to pass away was indeed Zaynab (radi Allahu anha).
However, in the narration that Imam Bukhari has recorded in his Tarikh, there is explicit mention of Umm al-Mu’minin Sawdah (radi Allahu anha), and here too, in this narration, the name of Sawdah (radi Allahu anha) appears, which is problematic. It is possible to answer this by saying that at the gathering in which this question was asked to the Prophet (sallallahu alayhi wa sallam), Zaynab (radi Allahu anha) was not present, and among the wives who were present, Sawdah (radi Allahu anha) was the first to pass away.
But in the narration of Ibn Hibban, it is stated that at that time all of his wives were present, none were absent; in this situation, even this possibility cannot stand.
Accordingly, Hafiz Ibn Hajar says:
“Qala lana Muhammad ibn Umar, meaning al-Waqidi: This hadith is mistakenly attributed to Sawdah, whereas it is actually about Zaynab bint Jahsh. She was the first of his wives to join him (in death), and she passed away during the caliphate of Umar, while Sawdah remained until she passed away during the caliphate of Muawiyah, in Shawwal, the year fifty-four. Ibn Battal said: In this hadith, the mention of Zaynab has been omitted, because the scholars of biography are agreed that Zaynab was the first among the wives of the Prophet (sallallahu alayhi wa sallam) to die. That is, the correct version is: ‘And Zaynab was the quickest among us, etc.’ However, what complicates this interpretation are those earlier narrations in which it is explicitly stated that the pronoun refers to Sawdah. And I have read in the handwriting of Hafiz Abu Ali al-Sadafi: The apparent wording of this narration is that Sawdah was the quickest, but this is contrary to what is well-known among the scholars, that Zaynab was the first among the wives to die. Then he transmitted it from Malik, from his narration from al-Waqidi. He said: And this is strengthened by the narration of Aisha bint Talhah. Ibn al-Jawzi said: This hadith is a mistake from some of the narrators, and it is astonishing that Bukhari did not point this out, nor did the authors of the commentaries, nor did al-Khattabi, who explained it and said: ‘The joining of Sawdah with him is among the signs of prophethood.’ All of this is a mistake; it is actually Zaynab, for she had the longest hand among them in giving charity, as Muslim narrated from the route of Aisha bint Talhah from Aisha, with the wording: ‘The one among us with the longest hand was Zaynab, because she used to work and give charity.’ And in another narration: ‘Zaynab was a woman skilled with her hands; she used to tan (leather), sew, and give charity in the way of Allah.’”

That is, al-Waqidi said to us that in this hadith, the narrator made a mistake.
In reality, the first to pass away was Zaynab (radi Allahu anha), whose death occurred during the caliphate of Umar (radi Allahu anhu), and Sawdah (radi Allahu anha) passed away during the caliphate of Muawiyah (radi Allahu anhu), in the year 54.
Ibn Battal said that in this hadith, the mention of Zaynab (radi Allahu anha) has been omitted, because it is agreed upon by the scholars of biography that among the Mothers of the Believers, the first to pass away was Zaynab bint Jahsh (radi Allahu anha), and in those narrations where the name of Sawdah (radi Allahu anha) appears, the narrator made a mistake.
Ibn al-Jawzi said that in this, some narrators mistakenly mentioned the name of Sawdah (radi Allahu anha), and it is astonishing that Imam Bukhari was not made aware of this, nor those who wrote the commentaries, who mentioned the name of Sawdah (radi Allahu anha) here, while it is actually Zaynab (radi Allahu anha), as is clear from the statement of Aisha (radi Allahu anha) in Sahih Muslim, that the one among us with the longest hand (i.e., the one who gave the most in charity) was Zaynab (radi Allahu anha).
She used to spin thread and earn money through other laborious work such as tanning, etc., and would give it in charity for the sake of Allah.
Some people have also said that in terms of measurement, Sawdah (radi Allahu anha) had long hands; at first, the wives of the Prophet (sallallahu alayhi wa sallam) thought that the wife with the longest hand would be the first to pass away.
But when Zaynab (radi Allahu anha) passed away, it became clear that what the Prophet (sallallahu alayhi wa sallam) meant by “long hands” was not physical length, but rather hands that gave in charity, and this distinction belonged to Zaynab (radi Allahu anha), who was the first to pass away. However, some narrators, due to their lack of knowledge, mentioned Sawdah (radi Allahu anha) here.
Some scholars have also reconciled by saying that when the Prophet (sallallahu alayhi wa sallam) made this statement, Zaynab (radi Allahu anha) was not present in that gathering; he spoke regarding the wives who were present at that time, and among them, Sawdah (radi Allahu anha) was the first to pass away. But even this reconciliation has been critiqued.
Hujjat al-Hind, Shah Waliullah Muhaddith Dehlawi (rahimahullah) says:
“And the apparent meaning of the hadith gives the impression that the first among the Mothers of the Believers to die after his (sallallahu alayhi wa sallam) passing was Sawdah, but it is not so. So reflect and do not be hasty in this matter, for it is among the slippery places for the feet.”
(Sharh Tarajim Abwab Bukhari)

Hadith Commentary:
(1)
Imam Hakim has said that this narration is according to the conditions of Muslim. Imam Bukhari rahimahullah, due to its fame, did not clarify the name in the mentioned hadith; thus, Allamah Kirmani writes that Imam Bukhari rahimahullah has narrated this incident with extreme brevity, and in it, all the pronouns refer predominantly to Zaynab bint Jahsh radi Allahu anha. (Fath al-Bari: 3/363) This is supported by the narration of Umm ‘Umarah, which Imam Hakim has mentioned in al-Mustadrak: ‘A’ishah radi Allahu anha said that the Messenger of Allah sallallahu alayhi wa sallam said to his wives: “The one among you with the longest hand will meet me first.” Umm al-Mu’minin ‘A’ishah radi Allahu anha said that after you (the Prophet), we used to measure our hands in the house of one of your wives, until Zaynab bint Jahsh radi Allahu anha passed away, even though she was not the one among us with the longest hands. At that time, we realized that what the Messenger of Allah sallallahu alayhi wa sallam meant was that the one who gives the most charity will meet me first. The respected lady used to work with her own hands; she would tan hides and dye them, and then give charity in the way of Allah from her earnings. (al-Mustadrak lil-Hakim: 4/25)

(2)
The connection of this hadith with the preceding discussion is that abundance in charity and self-sacrifice is only possible when, during times of health and well-being, one gives attention to sincerity and makes a habit of it. And Allah knows best.