Muslim

Hadith Commentary:
(1)
This hadith proves that beginning the prayer while sitting does not necessitate that the worshipper must complete the entire prayer sitting, because just as it is permissible to stand up after starting the prayer sitting, similarly, it is also permissible to sit down after starting the prayer standing. There is no difference between these two states. Furthermore, if a person is praying while lying down, and during the prayer he gains the strength to pray sitting or standing, then he should, based on his previous prayer, complete the remainder of his prayer sitting or standing. Some jurists do not permit this, but this hadith is contrary to their view.

(2)
Ibn Battal states that Imam Bukhari rahimahullah’s heading pertains to obligatory (fard) prayer, whereas the ahadith are about voluntary (nafl) prayer. Imam Bukhari rahimahullah has deduced from these ahadith that when it is permissible to sit in voluntary prayer without any excuse, yet still the Messenger of Allah sallallahu alayhi wa sallam would stand before bowing (ruku‘), then in obligatory prayer—where sitting without excuse is not permissible—when the excuse is removed, standing is even more appropriate, because now the excuse for sitting has ended.
(Fath al-Bari: 2/781)

Hadith Commentary:
This narration refutes the position of those scholars who hold that when the night prayer (tahajjud) is begun in a standing posture, the bowing (ruku) should also be performed standing, and when it is begun sitting, the bowing should also be performed sitting.
The evidence of these scholars is a narration reported from Aisha (radi Allahu anha) that the Messenger of Allah (sallallahu alayhi wa sallam), when he recited (Qur’an) standing, would perform the bowing standing, and when he recited sitting, he would perform the bowing sitting.
(Sahih Ibn Khuzaymah: 239/2)
From the aforementioned narration reported by Imam Bukhari (rahimahullah), it is understood that the Messenger of Allah (sallallahu alayhi wa sallam) would recite sitting, and when a few verses remained, he would stand and recite them, and then perform the bowing in a standing posture.
It should be noted that regarding the aforementioned narration of Sahih Ibn Khuzaymah, Hisham (rahimahullah) has taken a very strict stance.
The narrator of the hadith, Abu Khalid, says that when I mentioned this narration of Abdullah bin Shaqiq to Urwah (rahimahullah), he said that Abdullah bin Shaqiq is mistaken.
After this, he narrated the hadith reported from his father, Urwah (rahimahullah), which Imam Bukhari (rahimahullah) has presented.
Imam Ibn Khuzaymah (rahimahullah) says that in my view, there is no contradiction between these two narrations, because the meaning of the hadith reported from Abdullah bin Shaqiq is that when the entire recitation is performed standing, the bowing should also be performed standing, and when the entire recitation is performed sitting, the bowing should also be performed sitting.
And the meaning of the narration of Urwah (rahimahullah) is that if part of the recitation is performed sitting and part of it standing, then the bowing should be performed standing.
(Sahih Ibn Khuzaymah: 240/2)

Hadith Commentary: Benefits and Issues: It was the practice of the Messenger of Allah (sallallahu alayhi wa sallam) that he would recite lengthy portions of the Qur’an during the night prayer (tahajjud). Until he became advanced in age and his blessed body became heavy, he continued to recite while standing. When the signs of old age became apparent in his disposition and his body became burdensome, then standing for lengthy recitation became difficult. So he (sallallahu alayhi wa sallam) adopted this method: he would perform some units (rak‘ahs) standing and some sitting. And sometimes he did it in such a way that, instead of beginning the recitation while standing, he would start while sitting and then stand up at the end.

Therefore, it is permissible for a person to begin the prayer sitting and then stand up, or to begin the prayer standing and then sit down. Clearly, this need will arise in the situation when one intends to recite at length.

Hadith Commentary:
Benefits and Issues:
The manner of performing bowing (ruku‘) after reciting (the Qur’an) while sitting, and then standing up, is the same as has been mentioned above.

953. Commentary:
It is understood that in voluntary prayers (nawafil), it is permissible for a person to begin while sitting and then stand up during the recitation, or to begin while standing and then sit down in the middle.

1650. Commentary: Some have said that the method described in these two narrations pertains to the period of old age, as is explicitly mentioned in the second hadith. In the first two ahadith, the method before old age is described. Therefore, in reality, there is no contradiction, even though there appears to be a contradiction on the surface. Furthermore, this can also be attributed to the multiplicity of circumstances, meaning that the Messenger of Allah (sallallahu alayhi wa sallam) would sometimes pray standing and sometimes sitting. In this way, the apparent conflict between both types of ahadith is resolved.

Benefits and Issues:

➊ The tahajjud prayer of the Prophet sallallahu alayhi wa sallam used to be very lengthy, and he sallallahu alayhi wa sallam would recite long portions in it.

➋ While performing prayer standing, if part of the standing (qiyam) is done sitting, it is permissible. In this case, the bowing (ruku) and standing after bowing (qawmah) will be performed standing. However, if the entire standing (qiyam) is done sitting, then both the bowing (ruku) and standing after bowing (qawmah) will also be performed sitting.

Hadith Authentication:
[واخرجه البخاري 1119 و مسلم 731/112 من حديث مالك به]

Jurisprudential Points:
➊ If there is a valid Islamic excuse, it is permissible to perform the prayer while sitting; otherwise, standing is obligatory in the obligatory prayers.
➋ If a person begins the prayer sitting due to a valid Islamic excuse, and later during the second or any other rak‘ah his condition improves, he may perform the remainder of the prayer standing. Similarly, if a person begins the prayer standing but later his condition worsens, making it difficult for him to stand, he may perform the remainder of the prayer sitting according to his ability.
➌ It is permissible to perform voluntary (nafl) prayers while sitting, but the reward will be half. See [التمهيد 19/169]. However, the Prophet (sallallahu alayhi wa sallam) would receive the full reward.

Hadith Authentication:
[وأخرجه البخاري 1118، من حديث مالك به]

Jurisprudential Explanation:
➊ Even voluntary (nafl) prayers should be performed standing as much as possible; however, in case of an excuse, it is permissible to perform even obligatory (fard) prayers while sitting.
➋ The Messenger of Allah (sallallahu alayhi wa sallam) was the most God-fearing of all people and the most devoted in worship to Him.
➌ Also see: [الموطأ حديث سابق : 7، 112، 378]

Benefit:
In this hadith, it is mentioned that voluntary (nafl) prayers should also be performed standing. Some people have made it a habit to perform voluntary prayers sitting, even though they are healthy; this is contrary to the Sunnah. There is no harm in performing the prayer sitting due to illness or weakness. It should also be remembered that if one performs the prayer sitting without an excuse, only half the reward is attained.