Bukhari

Hadith Commentary:
Surah at-Talaq has been called the "small Surah an-Nisa" and Surah an-Nisa has been designated as the "great Surah an-Nisa."
In Surah at-Talaq, Allah has stated: ﴿وَأُولَاتُ الْأَحْمَالِ أَجَلُهُنَّ أَنْ يَضَعْنَ حَمْلَهُنَّ﴾ (: at-Talaq: 4)
Thus, pregnant women have been specified by the verse of Surah an-Nisa.
From this, it is derived that the position of Abdullah ibn Mas'ud (radi Allahu anhu) regarding the waiting period (‘iddah) of a pregnant woman was also that her ‘iddah is completed upon delivery, and the statement of Abdur Rahman ibn Abi Layla is proven incorrect.
There is no doubt in the narration of Ayyub as-Sakhtiyani.
As in the narration of Abdullah ibn ‘Awn, it is mentioned that he met Malik ibn ‘Amir or Malik ibn ‘Awf.
Imam al-Bukhari himself has connected this narration in the Tafsir of Surah at-Talaq.
The story of Subay‘ah mentioned in the narration is as follows: Subay‘ah’s husband, Sa‘d ibn Khawlah, died in Makkah while Subay‘ah was pregnant.
A few days after her husband’s death, she gave birth, and Abu as-Sanabil wished to marry her.
She asked the Messenger of Allah (sallallahu alayhi wa sallam) about the ruling.
He (sallallahu alayhi wa sallam) permitted her to marry.
It is thus known that the waiting period (‘iddah) of a pregnant woman ends with childbirth.
The statement of Abdullah ibn Mas‘ud (radi Allahu anhu) was that a pregnant woman will also complete her ‘iddah; if, after childbirth, there remain four months and ten days, then if a longer period remains, she should wait until childbirth.

Hadith Commentary:
➊
This hadith refers to an incident involving Sabi’ah bint al-Harith radi Allahu anha, the meaning of which is that her husband passed away during the Farewell Pilgrimage (Hajjat al-Wada’), and she was pregnant at the time. Before four months and ten days had passed, she delivered her child.
She presented herself before the Messenger of Allah sallallahu alayhi wa sallam to inquire about the ruling, and he said:
"Your waiting period (‘iddah) has ended with the delivery."
(Sunan Abi Dawud, al-Talaq, Hadith: 2306)
The implication of this hadith is that for a woman whose husband passes away, her waiting period is not four months and ten days, but rather until the delivery (wada’ al-haml), whether the delivery occurs soon or after a long time.

➋
This means that the ruling of the verse in Surah al-Baqarah applies only to non-pregnant women. Now, three scenarios arise:
© If a woman's husband dies and she is not pregnant, her waiting period is four months and ten days, as is understood from the verse in Surah al-Baqarah.
© If a woman is divorced and is pregnant, but her husband has not died, then her waiting period is until the delivery, as Allah the Exalted says:
"The waiting period for pregnant women is until the delivery."
(al-Talaq: 4/65)
© If a woman's husband dies and she is pregnant, there is a difference of opinion regarding this.
Is her waiting period until the delivery, or is it ab’ad al-ajalayni (i.e., the longer of the two periods)? The position of Ibn Abbas radi Allahu anhu is that her waiting period is ab’ad al-ajalayni.
(Sahih al-Bukhari, al-Tafsir, Hadith: 4909)
Ibn Abi Layla has attributed this same view to Abdullah ibn Mas’ud radi Allahu anhu, but this is not correct, because one of his students, Malik ibn ‘Amir radi Allahu anhu, has narrated that he said:
"You make things difficult for this widow, that if the duration of pregnancy exceeds four months and ten days, then the ruling is that her waiting period will not be completed before delivery, and you do not grant her concession that if the delivery occurs in less than four months and ten days, you do not consider the waiting period to be complete with the delivery." Then he said:
"Surah al-Nisa’ al-Qusra, i.e., Surah al-Talaq, was revealed after Surah al-Nisa’ al-Tawila, i.e., Surah al-Baqarah." Thus, the verse of Surah al-Talaq has specified (made an exception to) the verse of Surah al-Baqarah.

➌
The statement of Abdullah ibn Mas’ud radi Allahu anhu is the basis for the well-known juristic principle that if two instructions are received regarding an issue, the one that was revealed later is to be acted upon.
In any case, there is no contradiction between the verse 234 of Surah al-Baqarah and verse 4 of Surah al-Talaq, because the waiting period of four months and ten days is for those women who are not pregnant, and if she is pregnant, then her waiting period is until the delivery.
And Allah knows best.