Reference : Hisn al-Muslim 186

إِنِّي صَائِمٌ، 
إِنِّي صَائِمٌ
Innī  ṣā'im,
innī  ṣā'im.


I am fasting. 
I am fasting.

Reference:
Al-Bukhari, cf. Al-Asqalani, Fathul-BAri 4/103, Muslim 2/806.

Chapter: When insulted while fasting