They fasted then they went back to their homeland where Ramadaan had not yet begun

Praise be to Allah.

Firstly: 

In the answer to question no. 50487 we stated that the sighting of the moon may differ, so each country should fast according to its own sighting and they do not have to start fasting when the moon is sighted in another country. 

Secondly: 

It seems – and Allaah knows best – that if Ramadaan begins when a person is in one country then he should fast with the people of that country, even if he is travelling on that day to another country where the beginning of the month has not yet been announced. That is because fasting that day became obligatory for him when the month of Ramadaan began when he was in the first country, because Allaah says (interpretation of the meaning): 

“So everyone of you who is present during that month should spend it in fasting”

[al-Baqarah 2:185]

This person was present during the month so he has to fast.  

With regard to the command to count the number of days of the month, and the difference of opinion as to whether Ramadaan should be completed according to the reckoning of the first country, or according to the reckoning of the country to which he travelled, the basic principle that is mentioned by many of the scholars concerning this matter is that the one who travels to another country should follow the ruling of the country to which he has come, as it says in al-Majmoo’ by al-Nawawi (6/274). If the people in the second country complete the fasting as thirty days, he should fast with them, even if that means that he will have fasted thirty-one days. But if they fast for twenty-nine days, there is no problem in that case, because then he will have completed thirty days, and the month may be twenty-nine days or thirty days. 

Al-Nawawi (may Allaah have mercy on him) said in al-Majmoo’ (6/274): 

If he started to fast in one country then he travels to a distant country where they did not see the new moon when the people of the first country saw it, and he completes thirty days from the time when he fasted, if we assume that each country has its own ruling, then there are two points of view, the more sound of which is that he has to fast with them because he has now become one of them. 

What if he saw the new moon in one country, and celebrated Eid with them, then he travelled by ship to another country and finds the people there fasting? 

Shaykh Abu Muhammad said: He has to refrain from eating and drinking for the rest of that day, if we say that each country has its own ruling. End quote. 

It says in Tuhfat al-Muhtaaj (3/383) that Ibn Hajar al-Haytami (may Allaah have mercy on him) said: 

If we do not say that the people of the other country have to fast because of the differences in moonsighting, when a person travels there from a land where the moon was sighted, the more correct view is that he should join them in fasting until the end of their month, even if he has already completed thirty days, because by moving to where they are he has become like them. End quote. 

It says in al-Insaaf, which is a Hanbali book (3/273): 

It says in al-Ri’aayat al-Kubra: If he travels from a land where the moon was sighted on the night before Friday to a land where it was sighted the night before Saturday, and he has completed a month of fasting but they have not sighted the new moon, he should fast with them. End quote. 

We have previously quoted on this site many fatwas from contemporary scholars which affirm this ruling.  See the answers to questions no. 38101, 45545 and 71203. 

From the above it may be understood that the one who fasted and completed the fast on the first day of Ramadaan did the right thing, because you were in a country where the sighting of the moon had been confirmed for that day, so you were obliged to fast then, even if you entered your own country – where no announcement of Ramadaan had been made – during that day. 

Then when you travelled to your country in which the fasting began a day later than in the first country, you should continue fasting with the people there, even if that means that the number of days you fast is thirty-one. 

And Allaah knows best.