This excerpt is taken from the book of Fadhilat al-Shaykh Mubashir Ahmad Rabbani, may Allah have mercy on him, Ahkam wa Masail Ramadan.
Fasting and breaking the fast will be according to the city of residence:.
Question:.
I belong to East Asia. In our region, the Hijri month is one day later than that of the Kingdom of Saudi Arabia, and we students will travel to our homeland during the month of Ramadan this year. The Messenger of Allah, peace be upon him, said: Start fasting when you see the moon and end it when you see the moon, until the end of the hadith. We have started fasting in the Kingdom of Saudi Arabia. Then we will go to our country during the month of Ramadan, and it is possible that we will fast for thirty-one days until the end of Ramadan. My question is, what is the ruling regarding our fasts, and how many days should we fast?
Fatwa:.
Whether you fast in Saudi Arabia or anywhere else, then keep the fasts of the remaining month in your country, when the people there break their fasts, you should also break yours, even if it exceeds thirty days. Because the Prophet (peace be upon him) said:
الصوم يوم تصومون، والإفطار يوم تفطرون
"The day you start fasting is the day of fasting, and the day you break your fast is the day of iftar." However, if you cannot complete twenty-nine days of fasting, then fasting on the thirtieth day is obligatory for you. Because a lunar month cannot be less than 29 days.
Reference: (Musnad Bazar: 1/486, Musnad Tayalisi: 349, Ibn Khuzaymah: 3/231)