Hadith 434

Bulugh al-Maram

Book 2: The Book of Prayer
Hadith 434
وَفِي رِوَايَةٍ لَهُ: فَبَعَثَ مُنَادِيًا يُنَادِي: اَلصَّلَاةُ جَامِعَةٌ 1‏ .‏
In another narration of Muslim:

"He (ﷺ) sent an announcer to announce: The prayer is (to be offered) in congregation".