Dua for Sehri (Suhoor)
وَبِصَوْمِ غَدٍ نَّوَيْتُ مِنْ شَهْرِ رَمَضَانَ
Transliteration: Wa bisawmi ghadin nawaytu min shahri Ramadan
Translation: I intend to keep the fast for the month of Ramadan.
Reference: Common intention wording; niyyah is an act of the heart and this formula is not established as a Prophetic dua
Dua for Iftar
اللَّهُمَّ إِنِّي لَكَ صُمْتُ وَبِكَ آمَنْتُ وَعَلَيْكَ تَوَكَّلْتُ وَعَلَى رِزْقِكَ أَفْطَرْتُ
Transliteration: Allahumma inni laka sumtu wa bika aamantu wa ‘alayka tawakkaltu wa ‘ala rizqika aftartu
Translation: 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.
Reference: Commonly recited Iftar wording; the related report in Sunan Abi Dawud 2358 has weakness in its chain