´It was narrated that Samurah bin Jundab said:` “The Messenger of Allah (ﷺ) commanded us to greet our Imam with Salam, and to greet one another with Salam.”
Hadith Referenceسنن ابن ماجه / كتاب إقامة الصلاة والسنة / 922
Hadith Gradingالألبانی:ضعيف | زبیر علی زئی:ضعيف, إسناده ضعيف, سنن أبي داود (1001), انوار الصحيفه، صفحه نمبر 411, -
Narrated Samurah ibn Jundub: The Prophet ﷺ commanded us to respond to the salutation of the imam. and to love each other, and to salute each other.
Shaykh Umar Farooq Saeedi
1001. Commentary: Reply to the Imam’s Salam. This means that when turning for salam (salutation of peace) at the end of the prayer, the followers (muqtadis) should intend to reply to the salam of the Imam. However, this narration is weak in its chain of transmission, and thus no ruling can be established from it. Nevertheless, the subsequent part of the narration, which commands mutual love and greeting one another with salam, is correct, because both of these matters are established from authentic ahadith.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 1001