Narrated Abu Huraira: The Prophet said, "The young should greet the old, the passer by should greet the sitting one, and the small group of persons should greet the large group of persons. "
Hadith Referenceصحيح البخاري / كتاب الاستئذان / 6231
Hadith Gradingمحدثین:أحاديث صحيح البخاريّ كلّها صحيحة