Sahih al-Bukhari 6008
Narrated Abu Sulaiman and Malik bin Huwairith:
We came to the Prophet (ﷺ) and we were (a few) young men of approximately equal age and stayed with 
him for twenty nights. Then he thought that we were anxious for our families, and he asked us whom 
we had left behind to look after our families, and we told him. He was kindhearted and merciful, so he 
said, "Return to your families and teach them (religious knowledge) and order them (to do good 
deeds) and offer your prayers in the way you saw me offering my prayers, and when the stated time 
for the prayer becomes due, then one of you should pronounce its call (i.e. the Adhan), and the eldest 
of you should lead you in prayer.
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا إِسْمَاعِيلُ، حَدَّثَنَا أَيُّوبُ، عَنْ أَبِي قِلاَبَةَ، عَنْ أَبِي سُلَيْمَانَ، مَالِكِ بْنِ الْحُوَيْرِثِ قَالَ أَتَيْنَا النَّبِيَّ صلى الله عليه وسلم وَنَحْنُ شَبَبَةٌ مُتَقَارِبُونَ، فَأَقَمْنَا عِنْدَهُ عِشْرِينَ لَيْلَةً، فَظَنَّ أَنَّا اشْتَقْنَا أَهْلَنَا، وَسَأَلَنَا عَمَّنْ تَرَكْنَا فِي أَهْلِنَا، فَأَخْبَرْنَاهُ، وَكَانَ رَفِيقًا رَحِيمًا فَقَالَ ‏
"‏ ارْجِعُوا إِلَى أَهْلِيكُمْ فَعَلِّمُوهُمْ وَمُرُوهُمْ، وَصَلُّوا كَمَا رَأَيْتُمُونِي أُصَلِّي، وَإِذَا حَضَرَتِ الصَّلاَةُ فَلْيُؤَذِّنْ لَكُمْ أَحَدُكُمْ، ثُمَّ لِيَؤُمَّكُمْ أَكْبَرُكُمْ ‏"‏‏.‏