Sunan Abi Dawud 5210
سنن أبي داود#5210SahihNarrated Ali ibn AbuTalib: 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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Zubair Ali ZaiHasan
In-book reference: 43:438