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).[Al-Bukhari and Muslim].
App reference: Book 6, Hadith 24
Arabic/English book reference: Book 6, Hadith 868