AbuDawud said: Al-Hasan ibn Ali traced this tradition back to the Prophet ﷺ: When people are passing by, it is enough if one of them gives a salutation on their behalf, and that it is enough for those who are sitting if one of them replies. (Using translation from Abū Dāʾūd 5210)
أَنْ يَرُدَّ أَحَدُهُمْ