Sunan an-Nasa'i, Volume 1, Book 7, Hadith 636 (DarusSalam)

It was narrated that Malik bin Al-Huwairith said: "We came to the Messenger of Allah and we were young men close in age. He let us stay with him for twenty days. The Messenger of Allah was merciful and compassionate, and he thought that we were missing our families; he asked us about those whom we had left behind of our families, so we told him, and he said: 'Go back to your families, stay with them and teach them. Tell them when the time for prayer comes; let one of you call the Adhan and let the oldest of you lead the prayer.'"

أَخْبَرَنِي زِيَادُ بْنُ أَيُّوبَ، قَالَ حَدَّثَنَا إِسْمَاعِيلُ، قَالَ حَدَّثَنَا أَيُّوبُ، عَنْ أَبِي قِلاَبَةَ، عَنْ مَالِكِ بْنِ الْحُوَيْرِثِ، قَالَ أَتَيْنَا رَسُولَ اللَّهِ صلى الله عليه وسلم وَنَحْنُ شَبَبَةٌ مُتَقَارِبُونَ فَأَقَمْنَا عِنْدَهُ عِشْرِينَ لَيْلَةً وَكَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم رَحِيمًا رَفِيقًا فَظَنَّ أَنَّا قَدِ اشْتَقْنَا إِلَى أَهْلِنَا فَسَأَلَنَا عَمَّنْ تَرَكْنَاهُ مِنْ أَهْلِنَا فَأَخْبَرْنَاهُ فَقَالَ ‏ "‏ ارْجِعُوا إِلَى أَهْليِكُمْ فَأَقِيمُوا عِنْدَهُمْ وَعَلِّمُوهُمْ وَمُرُوهُمْ إِذَا حَضَرَتِ الصَّلاَةُ فَلْيُؤَذِّنْ لَكُمْ أَحَدُكُمْ وَلْيَؤُمَّكُمْ أَكْبَرُكُمْ ‏" ‏ ‏.‏

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also referenced under: Book 7, Hadith 642 (In-Book)