When breaking the fast - Iftar
اللَّهُمَّ اِنِّى لَكَ صُمْتُ وَبِكَ امنْتُ [وَعَلَيْكَ تَوَكَّلْتُ] وَعَلَى رِزْقِكَ اَفْطَرْتُ
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
["wa ‘alayka tawakkaltu" is quoted in some books of knowledge - but not all, hence it is in brackets]
[Abu Dawud]

Transliteration:
Allahumma Inni laka sumtu wa bika amantu [wa alayka tawakkalto] wa ‘ala rizqika aftartu