Musannaf Ibn Abi Shayba 3:3170

Waki’ narrated to us, from Shaddad Abu Talha, from Mu’awiyah ibn Qurrah, who said: I reached thirty men from the Muzaynah tribe, all of whom had been stabbed or struck. When the day of Friday arrived, they would perform ghusl, wear their best clothes, and apply perfume. Then they would go out, pray two rak'ahs, and sit to spread knowledge.