Lady Umm Hani (may Allah be pleased with her) narrated: On the day of the conquest of Makkah, the Messenger of Allah (peace and blessings be upon him) came to our house, so I presented a drink to him, or it was presented to him, and he drank it. Then he handed it to me. I said: O Messenger of Allah! I am fasting. So the Messenger of Allah (peace and blessings be upon him) said: "The one who keeps a voluntary fast is his own master (ruler); if you wish, complete your fast, and if you wish, break it."
Hadith Referenceمسند اسحاق بن راهويه / كتاب الصوم / 422
Hadith Takhrij«سنن ابوداود ، كتاب الصيام ، باب النية فى الصيام ، رقم : 2456 . سنن ترمذي ، ابواب الصوم ، باب ماجاء فى افطار الصائم المتطوع ، رقم : 731 . قال الشيخ الالباني : صحيح .»