Hadithcore
Riyad as-Salihin, 868

Usamah bin Zaid (May Allah be pleased with him) reported:

The Prophet (ﷺ) passed by a mixed company of people which included Muslims, polytheists and Jews, and he gave them the greeting (i.e., saying As- Salamu 'Alaikum). <b>[Al-Bukhari and Muslim]</b>.

وعن أسامة رضي الله عنه أن النبي صلى الله عليه وسلم مر على مجلس فيه أخلاط من المسلمين والمشركين -عبدة الأوثان واليهود- فسلم عليهم النبي صلى الله عليه وسلم‏"‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏‏.‏

References1 variant
In-Book Reference
Book 5, Hadith 25
Sharh · explanationclick to expand
<b>Guidance from the Hadith:</b><br> 1) It is permissible to give the greeting of peace to a gathering that comprises a mix of Muslims and disbelievers with the intention of addressing the Muslims among them only with the greeting of peace.<br> 2) One of the reasons behind the prohibition of initiating the greeting of peace to a disbeliever is that “Islam is superior and nothing is more superior to it.” [Narrated by Al-Darāqutni; classified as Sahih] (authentic)]