´Narrated Usamah bin Zaid:` that the Prophet (ﷺ) passed by a gathering in which the Muslims and the Jews were mixed, so he gave the Salam to them.
Explanation & Benefits
Shaykh Dr. Abdur Rahman Freywai
Explanation:
1:
It is understood from this that in a gathering where both Muslims and non-Muslims are present, one should address the Muslims specifically and say "as-salamu alaykum" to them.
Source: Sunan al-Tirmidhi – Majlis ‘Ilmi Dar al-Da‘wah, New Delhi Edition, Page: 2702