´It was narrated hat Aishah said:` "The Messenger of Allah (ﷺ) used to pray standing and sitting. If he started to pray standing, he would bow standing and if he started to pray sitting, he would bow sitting."
Hadith Referenceسنن نسائي / كتاب قيام الليل وتطوع النهار / 1648
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:صحيح مسلم
Hafsa, daughter of 'Abdul Rahman bin Abu Bakr, reported that 'A'isha narrated to her that she and the Apostle of Allah (ﷺ) took a bath from the same vessel which contained water equal to three Mudds or thereabout.
Shaykh Maulana Abdul Aziz Alvi
Hadith Commentary:Benefits and Issues: One mudd (مد) of water amounts to two ratl, which is a quarter of a sa’ (صاع). In this way, the water will be slightly more than one liter, and in three mudd, the water will be less than three and a half liters. From this, it is understood that the Prophet (sallallahu alayhi wa sallam) sometimes managed with three mudd of water instead of three sa’ for ritual bath (ghusl), or in such a case, he may not have performed the ritual bath together (i.e., with someone else). Rather, due to the vessel being small, he would have performed the ritual bath one after the other. According to some, mudd here is in the meaning of sa’.
Source: Tuhfat al-Muslim: Commentary on Sahih Muslim, Page: 730
Aishah said: The Messenger of Allah ﷺ used to pray standing at night for a long time, and used to pray sitting at night for a long time. When he prayed standing, he bowed standing, and when he prayed sitting, he bowed sitting.
Shaykh Umar Farooq Saeedi
955. Commentary: The best practice is that when the recitation (qira’ah) is performed standing, then the bowing (ruku‘) should also be performed standing; and if the recitation is performed sitting, then the bowing should also be performed sitting... This, and the aforementioned scenario—i.e., if a portion of the rak‘ah is performed standing and a portion sitting—is also permissible.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 955