Hadith 4:355
Mu'adh ibn Mu'adh narrated to us, from Ibn 'Awn, who said: Muhammad [ibn Sirin] used to fast the ten, the ten of Dhu al-Hijjah, all of it. So when the ten had passed and the days of Tashriq had passed, he would break his fast for nine days, equal to what he had fasted.
حدثنا معاذ بن معاذ عن بن عون قال كان محمد يصوم العشر عشر ذي الحجة كله فإذا مضى العشر ومضت ايام التشريق أفطر تسعة أيام مثل ما صام