Answered by Shaykh Faraz Rabbani
Are we allowed to eat fish burgers from the fast-food restaurant in UK – like Mc Donald, which there may be possibility of using the same oil – which was used for frying the Haram chicken (but not pork). If the fried fish is fried using the same oil that is used for frying the Haraam chicken – would the fish be Halaal.
Walaikum assalam wa rahmatullah,
I pray that this finds you well, and in the best of health and spirits. May Allah grant you all good and success in this life and the next.
One is supposed to be particularly scrupulous about food and where one eats from, as this has been particularly emphasized in Prophetic guidance. And it is the transmitted experience of the scholars and righteous that eating doubtful food or food from dubious sources hurts one’s religious uprightness and stunts one’s spiritual growth.
With regards to your question:
[1] If you are sure that the restaurant uses separate oil to fry the halal food (such as fish), then it would be permitted without dislike to eat it–with the remaining recommendedness of avoiding the food of people of heedlessness.
[2] If you aren’t sure, then basic religious scrupulousness would entail leaving such food.
[3] If you know that they use the same oil, then it would be haram to consume such food.
The Beloved Messenger of Allah (peace and blessings be upon him) said, “You don’t leave anything for the sake of Allah except that Allah replaces it with something better for you.” [Related by Ahmad]
And Allah alone gives success.
Faraz Rabbani