The intention of fasting:
Intention (Niyyah) is the name of a firm resolve. Speaking it out is not a condition. However, articulating as per the Niyyah in one’s heart is Mustahab (commendable). If the intention for fasting is made in the night, then the following words should be used:
Transliteration: Nawaytu An Asauma Ghadal Lillahi Ta’ala Min Saumi Ramadhan.
Or briefly:
Transliteration: Nawaytu Bi Saumi Ghadin
Translation: I have made the intention that for the sake of Allah Ta’ala, I will keep a fast of Ramadhan tomorrow.
Or the smaller one:
Translation: I have made the Niyyah for tomorrow’s fast.
If the Niyyah is being made in the day, then the following words should be said:
Transliteration: Nawaytu An Asauma Li Hadhal Yaum
Translation: I am making the Niyyah for today’s fast.
There is no problem if the words “Insha Allah Ta’ala” are added as a form of blessing.
Having Sehri is also equal to intention, as Sehri is taken only with the intention of fasting. However, it will not be considered as a Niyyah if while having Sehri or after Sehri, one makes the intention of not fasting.
If someone makes the Niyyah in the heart while in Salaat, that Niyyah is also valid.
It is necessary to make a separate Niyyah for every fast in Ramadhan. One Niyyah for all the fasts is not correct.
For the fasts of Ramadhan ,Wajib Mu’ayyan fasts and Nafl fasts, the time for Niyyah is from sunset (previous) to sometime before the Shariah Midday (Nisf Nahar Shara’ee). If someone makes the Niyyah within this time, it is valid. After this, there cannot be any Niyyah for fasts. However, it is Mustahab (commendable) that the intention should be made in the night itself. Also, for these fasts, it is not necessary to specify it that this is the fast of Ramadhan or a Wajib Mu’ayyan or Nafl. Regardless of whether it is specified or simply the intention of fast is (or Nafl) is made, in Ramadhan, the fasts of Ramadhan will be kept. On the day of Wajib Mu’ayyan, those fasts will be done and in other days Nafl. However, it is better to specify it.
The Shariah day is from true dawn (Subah Sadiq) to sunset. The customary day is from sunrise to sunset. For example if true dawn is at 4 o’clock and sunset is at 6 o’ clock, then the Shariah Day is of 14 hours and the Niyyah should be made before 11 o’ clock.
In Qaza fasts (of Ramadhan), Wajib Gair Mu’ayyan fasts, the fasts of atonement/expiation (Kaffara) and in the Qaza of those Nafl fasts, which were started, but not completed for some reason, it is necessary to make the Niyyah before the sunrise. Also, for these fasts, it is necessary to specify these fasts while making Niyyah.
Making the Niyyah for any fast before sunset (for the fast of the next day) is not correct.
There should be no doubt in Niyyah, otherwise the fast will not be valid. For example, thinking that if tomorrow there is a function, I will not fast, if there is no function, I will fast.
Making the Niyyah of Iftaar (breaking the fast) while fasting does not make the Niyyah of fasting invalid, until the Iftaar is not done.