The necessity of saying the Takbir, i.e., Allahu Akbar (Allah is the Most Great) and the commencement of As-Salat (the prayer)

English translation

Narrated Anas bin Malik Al-Ansari:

Allah's Messenger (ﷺ) rode a horse and fell down and the right side of his body was injured. On that day he prayed one of the prayers sitting and we also prayed behind him sitting. When the Prophet (ﷺ) finished the prayer with Taslim, he said, "The Imam is to be followed and if he prays standing then pray standing, and bow when he bows, and raise your heads when he raises his head; prostrate when he prostrates; and if he says "Sami`a l-lahu liman hamidah", you should say, "Rabbana wa laka l-hamd.:

English translation

Narrated Anas bin Malik:

Allah's Messenger (ﷺ) fell from a horse and got injured so he led the prayer sitting and we also prayed sitting. When he completed the prayer he said, "The Imam is to be followed; if he says Takbir then say Takbir, bow if he bows; raise your heads when he raises his head, when he says, 'Sami`a l-lahu liman hamidah say, 'Rabbana laka l-hamd', and prostrate when he prostrates."

English translation

Narrated Abu Huraira:

The Prophet (ﷺ) said, "The Imam is to be followed. Say the Takbir when he says it; bow if he bows; if he says 'Sami`a l-lahu liman hamidah', say, ' Rabbana wa laka l-hamd', prostrate if he prostrates and pray sitting altogether if he prays sitting."