Sahih Muslim Book 4, Hadith 85
The Messenger of Allah (ﷺ) fell down from a horse and his right side was grazed, and the rest of the hadith is the same with the addition of these words:" When he (the Imam) says prayer standing, you should also do so."
The Messenger of Allah (ﷺ) fell down from a horse and he was grazed and he led the prayer for us sitting, and the rest of the hadith is the same.
The Messenger of Allah (ﷺ) rode a horse and fell down from it and his right side was grazed, and the rest of the hadith is the same, and (these words) are found in it:" When he (the Imam) says prayer in an erect posture, you should also say it in an erect posture."