Answered by Sayyidi Habib `Umar bin Hafiz (may Allah preserve him and benefit us by him).
Is it permissible to feed non-Muslims in Ramadan during the day?
Non-Muslims are not required to fast, so it is permissible to feed them during the day in Ramadan. It is our duty to invite them to Islam. Once they have entered Islam they are required to fast. We should not, however, give them food if they will then eat it in front of Muslims who are fasting. In a country in which the majority of people are Muslim, non-Muslims should not eat and drink openly, for this may encourage Muslims to do the same.
If this is not the case, it is permissible to feed them during the day but it is preferable to do so at night so that they are aware of the sanctity of Ramadan. There is a great reward in feeding non-Muslims and it is a means of calling them to Allah.
It would be a sin to feed a Muslim who is not a traveller and who is able to fast. There is no harm in feeding a traveller or someone who is unable to fast due to illness or old age.