Dua for Opening Fast

ذَهَبَ الظَّمَأُ ، وَابْتَلَّتِ الْعُرُوْقُ ، وَثَبَتَ الْأَجْرُ إِنْ شَاءَ اللّٰهُ.
اَللّٰهُمَّ لَكَ صُمْتُ وَعَلَىٰ رِزْقِكَ أَفْطَرْتُ.

Translation :

The thirst has gone, the veins have been moistened, and the reward has been secured, if Allah wills.

O Allah, for You I have fasted, and with Your provision I have broken my fast.

Transliteration :

Dhahaba-ẓ-ẓama’, wa-b-tallati-l-ʿurūq, wa thabata-l-ajru in shā’a-llāh.

Allāhumma laka ṣumtu wa ʿalā rizqiqa afṭart.

Hadith:

ʿAbdullāh b. ʿUmar (raḍiy Allāhu ‘anhuma) said the Messenger of Allah ﷺ said [the above] when he broke his fast. (Abū Dāwūd 2357)

The Messenger of Allah ﷺ said: “The deeds of the people are presented (to Allah) on Mondays and Thursdays. So I like that my actions be presented whilst I am fasting.” (Tirmidhī)

And He ﷺ said: “Fasting three days of each month is equivalent to fasting for a lifetime. The days of al-Bīdh are: the thirteenth, fourteenth and fifteenth.” (Nasā’ī)
When the Messenger of Allah ﷺ broke his fast he would say [the above]. (Abū Dāwūd 2358)