Sahih Muslim – Hadith No : 412

‘A’isha reported: The Messenger of Allah (may peace be upon him) fell ill and some of his Companions came to inquire after his health. The Messenger of Allah (may peace he upon him) said prayer sitting, while (his Companions) said it (behind him) standing. He (the Holy Prophet) directed them by his gesture to sit down, and they sat down (in prayer). After finishing the (prayer) lie (the Holy Prophet) said: The Imam is appointed so that be should be followed, so bow down when lie bows down, and rise rip when he rises up and say (prayer) sitting when he (the Imam) says (it) sitting.

Hadith In Arabic Text :

حدثنا أبو بكر بن أبي شيبة، حدثنا عبدة بن سليمان، عن هشام، عن أبيه، عن عائشة، قالت اشتكى رسول الله صلى الله عليه وسلم فدخل عليه ناس من أصحابه يعودونه فصلى رسول الله صلى الله عليه وسلم جالسا فصلوا بصلاته قياما فأشار إليهم أن اجلسوا ‏.‏ فجلسوا فلما انصرف قال ‏”‏ إنما جعل الإمام ليؤتم به فإذا ركع فاركعوا وإذا رفع فارفعوا وإذا صلى جالسا فصلوا جلوسا ‏”‏ ‏.‏

Chapter : The Book of Prayers – كتاب الصلاة