Dua (Prayer) of Fasting

The following dua (prayers) are recited at the beginning and end of the fast to indicate and affirm the intention of the fast.
A person’s intention when fasting, is to bring him/herself closer to God.
The purpose of making an intention before every deed is to remind our inner self and confirm with our verbal intention that we seek the pleasure of God in our all actions.

Dua (Prayer) at the Beginning of the Fast 1
وَبِصَوْمِ غَدٍ نَّوَيْتَ مِنْ شَهْرِ رَمَضَا
Wa bisawmi ghadinn nawaiytu min shahri ramadan
I intend to keep the fast for tomorrow in the month of Ramadan
Or you can also recite the flowing:
Dua (Prayer) at the Beginning of the Fast 2
نـَوَيْتُ صَوْمَ غـَدٍ عَـنْ ا َدَاءِ فـَرْضِ شـَهْرِ رَمـَضَانَ هـَذِهِ السَّـنـَةِ لِلـّهِ تـَعَالىَ
Nawaitu sauma ghadin anadai fardu syahri ramadhana hadzihissanati lillahitaala
I intend to do obligatory fast tomorrow in the month of Ramadan this year because of Allah

Dua (Prayer) at the End of the Fast
اللَّهُمَّ اِنِّى لَكَ صُمْتُ وَبِكَ امنْتُ وَ عَلى رِزْقِكَ اَفْطَرْتُ
Allahumma inni laka sumtu wa bika aamantu wa alayka tawakkaltu wa ala rizq-ika-aftartu
O Allah! I fasted for You and I believe in You and I put my trust in You and I break my fast with Your sustenance

Hadith of Intention
Umar Ibn Al-Khattab relates that he heard the Messenger of God صلى الله عليه و سلم say : “Actions are but by intention and every man shall have but that which he intended. Thus he whose migration was for Allah and His messenger, his migration was for Allah and His messenger, and he whose migration was to achieve some worldly benefit or to take some woman in marriage, his migration was for that for which he migrated.” ~ Related by Bukhari and Muslim
This is an extremely comprehensive and rich Hadith of the Prophet صلى الله عليه و سلم that reflects the core of the Islamic Faith.
Imam Bukhari selected the first hadith, ‘Innamal a’malu binniyat’ of Sahih Bukhari as an introduction to the whole collection to show the sincerity of purpose of the author. It reminds the reader that good and noble deeds inculcated by the Hadith found therein will only bear fruit if there is sincerity attached to their intentions and would be meaningless if the motive is not sincere.

Source: IslamiCity