Sunnah.com reference : Book 2, Hadith 434English translation : Book 2, Hadith 0Arabic reference : Book 2, Hadith 504
In another narration of Muslim:
"He (ﷺ) sent an announcer to announce: The prayer is (to be offered) in congregation".
وَفِي رِوَايَةٍ لَهُ: فَبَعَثَ مُنَادِيًا يُنَادِي: اَلصَّلَاةُ جَامِعَةٌ  1‏ .‏‏1 ‏- مسلم برقم (901)‏ (4)‏.‏