Please quote all available Ahadith in this regard, and provide an answer for each of the 4 cases. Also did it vary from, say like Fajr Salaat to Dhuhr?
Whenever Rasulullah (Sallallaahu Alayhi Wasallam) lead the congregational
Salaat, he always considered his followers. It is mentioned in Sahih Bukhari
that whever he head the crying of a baby, he shortened the Salaat.
However, in the Nafl Salaat, Nabi (Sallallaahu Alayhi Wasallam) used to
stand for long hours until his blessed feet became swollen. (Bukhari). His
Ruku and Sajda were according to the length of Qiyaam.
Awf (Radhiallaahu Anhu) narrates, ‘I was once with Rasulullah (Sallallaahu
Alayhi Wasallam). He brushed his teeth with Miswaak, performed Wudhu and
stood up for Salaat. I also availed of the opportunity to join him. He
recited Surah Baqarah in his first Rakaat. He would pray for mercy when he
recited any verse extolling the grace of Allah Ta’ala and would supplicate
for divine forgiveness when reciting any verse referring to his wealth. He
took as much time in Ruku and Sajdah each as he had taken in Qiyaam.’
(Fadhaail-e-Aamaal pg.87)
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai