The Hadith of Ibn Buhainah is a Hasan Hadith, and this is acted upon according to some of the people of knowledge. It is the opinion of Ash-Shafi'i, he held the view that all prostrations for As-Sahw were to be performed before the Salam, saying: "This one abrogates the other Ahadith" and he mentioned that the last action of the Prophet (ﷺ) was according to this.
Ahmad and Ishaq said: "When a man stands up after two Rak'ah, then he performs the prostrations for As-Sahw before the Salam according to the Hadith of Ibn Buhainah."
'Abdullah bin Buhainah is 'Abdullah bin Malik Ibn Buhainah (because) Malik is his father and Buhainah is his mother.
I was informed of this by Ishaq bin Mansur from 'Ali bin Al-Madini.
Abu 'Eisa said: The people of knowledge differ over when a man is to perform the prostrations of As-Sahw, is it before the Salam or after it. Some of them thought that her performs them after the Salam. This is the view of Sufyan Ath-Thawri and the people of Al-Kufah. Some of them said he performs them before the Salam. This is the view of most of the Fuqaha among the people of Al-Madinah, like Yahya bin Sa'eed, Rabi'ah, and others. This is also the saying of Ash-Shafi'i.
Some of them said when he adds to the Salat, then it is after the Salam, and when he leaves something out, then before the Salam. This is the view of Malik bin Anas.
Ahmad said: "Whatever is reported from the Prophet (ﷺ) about the prostrations from As-Sahw then it is acted upon in either case." He saw that when one stands after Rak'ah then according to the Hadith of Ibn Buhainah, he is to perform the prostrations before the Salam. When he prays five for Zuhr, then performs the prostrations after the Salam, and if he says Salam after two Rak'ahs of Zuhr or 'Asr then he performs the prostrations after the Salam. All of them are to be acted upon depending upon the case, and in the cases where nothing is reported from the Prophet (ﷺ), then two prostrations are performed for As-Sahw before the Salam.
Ishaq said the same as Ahmad about all of this, with the exception that he said that for every case of As-Sahw that is not mentioned from the Prophet (ﷺ), then if it is an addition to the Salat, then prostrations are performed after the Salam, and if it is something that was left out, then the prostrations are performed before the Salam.
Jami` at-Tirmidhi Book 2, Hadith 244
The Prophet (ﷺ) delivered a sermon and said, "Zaid took the flag and was martyred, and then Ja`far took
the flag and was martyred, and then `Abdullah bin Rawaha took the flag and was martyred too, and
then Khalid bin Al-Walid took the flag though he was not appointed as a commander and Allah made
him victorious." The Prophet (ﷺ) further added, "It would not please us to have them with us." Aiyub, a
sub-narrator, added, "Or the Prophet, shedding tears, said, 'It would not please them to be with us.'"
Sahih al-Bukhari Book 56, Hadith 16
Yahya related to me from Malik from Ibn Shihab from Humayd ibn
Abd ar-Rahman ibn Awf from Abu Hurayra that the Messenger of Allah,
may Allah bless him and grant him peace, said, "Whoever hands over two
of any type of property in the way of Allah is called to the Garden,
with the words 'O slave of Allah! This is good!' Whoever is among the
people of prayer, is called from the gate of prayer. Whoever is among
the people of jihad is called from the gate of jihad. Whoever is among
the people of sadaqa, is called from the gate of sadaqa. Whoever is
among the people of fasting, is called from the gate of the well-
watered. (Bab ar-Rayyan)."
Abu Bakr as-Siddiq said,
"Messenger of Allah! Is it absolutely necessary that one be called
from one of these gates? Can someone be called from all of these
gates?" He said, "Yes, and I hope you are among them ."
21.20
Acquisition of the Land of Those who Surrender from the People of
Dhimma
Muwatta Malik Book 21, Hadith 51