وَبِصَوْمِ غَدٍ نَوَيْتُ مِنْ شَهْرِ رَمَضَانَ
Wa bisawmi ghadin nawaitu min shahri Ramadan
I intend to fast tomorrow in the month of Ramadan.
The intention (niyyah) for fasting should be made before Fajr. It can be a verbal statement or simply the resolve in your heart. The Prophet ﷺ said: "Whoever does not make the intention to fast before Fajr, there is no fast for him."
Related Du'as
اللَّهُ أَكْبَرُ اللَّهُ أَكْبَرُ لَا إِلَٰهَ إِلَّا اللَّهُ وَاللَّهُ أَكْبَرُ اللَّهُ أَكْبَرُ وَلِلَّهِ الْحَمْدُ
Allah is the Greatest, Allah is the Greatest. There is no deity except Allah. And Allah is the Greatest, Allah is the Greatest, and to Allah belongs all praise.
Sahihاللَّهُمَّ أَهِلَّهُ عَلَيْنَا بِالْأَمْنِ وَالْإِيمَانِ وَالسَّلَامَةِ وَالْإِسْلَامِ رَبِّي وَرَبُّكَ اللَّهُ
O Allah, let this moon rise upon us with security, faith, safety, and Islam. My Lord and your Lord is Allah.
Hasanاللَّهُمَّ بَلِّغْنَا رَمَضَانَ وَأَعِنَّا عَلَى صِيَامِهِ وَقِيَامِهِ وَتَقَبَّلْهُ مِنَّا
O Allah, let us reach Ramadan, help us to fast and pray in it, and accept it from us.
Hasanاللَّهُمَّ إِنَّكَ عَفُوٌّ كَرِيمٌ تُحِبُّ الْعَفْوَ فَاعْفُ عَنِّي
O Allah, You are the Pardoner, the Most Generous, and You love to pardon, so pardon me.
Sahih