Hadith 4:894
Waki’ narrated to us, from Yazid, the freed slave of al-Sahba’, from a man whom he named, from Anas, who said: "There shall be no 'Ithnini' (fasting specifically on Mondays), nor 'Khamisi' (fasting specifically on Thursdays), nor 'Rajabi' (fasting specifically in the month of Rajab)."
حدثنا وكيع عن يزيد مولى الصهباء عن رجل قد سماه عن أنس قال لا يكون أثنينيا ولا خميسيا ولا رجبيا