Q. There are many impious people here in Bangladesh, is it permissible to accept their invitations and it is permissible to eat from Hindus cooking the food?
It is permitted to accept the invitation of an impious person. It is also permitted to eat from foods prepared by Hindus in market places or local village neighbours – but caution should prevail. In al-Fatawa al-Hindiyya it has Imam Muhammad Ibn al-Hasan al-Shaybani’s (Allah have mercy on him) ruling:
“It is considered somewhat disliked to eat and drink from utensils owned by mushrikun before they are washed but nevertheless despite that it is permitted to eat and drink from them without them being washed and it would not be considered unlawful. However, this is only the case if one is not aware of the utensils being impure. If one is aware of the impurity of the utensils then it would not be permitted to eat and drink from them before them being washed. And if one does eat or drink from them then it would be unlawful…”
ويكره الأكل والشرب في أواني المشركين قبل الغسل ومع هذا أكل وشرب فيها قبل الغسل جاز ولا يكون أكلا ولا شربا حراما وهذا إذا لم يعلم بنجاسة الأواني فأما إذا علم فانه لا يجوز أن يشرب فيها ويأكل منها قبل الغسل ولو شرب أو أكل كان شاربا أو آكلا حراما
And Allah knows best.
 See al-Fatawa al-Hindiyya, 5:347.