Question:
I thought something was haram and promised Allah ﷻ that I would never do it. Later I learned it is halal. Can I break that promise?
Answer:
The Prophetﷺ once made honey forbidden upon himself due to a family matter, even though honey is halal. Allah ﷻ revealed a verse asking: “O Prophetﷺ, why do you forbid what Allah ﷻ has made lawful for you, seeking the pleasure of your wives?” Allah ﷻ reminded him not to do that.
However, since he had sworn an oath, Allah ﷻ explained how to expiate broken oaths. If someone swears not to do something and later realizes it is wrong to maintain that oath, they can break it but must offer expiation. Surah Al-Ma’idah (5:89) states that the expiation for breaking an oath is to feed ten poor people with average food given to one’s family, or clothe ten poor people, or free a slave. If none of these are possible, then one must fast for three days.
So if you unknowingly declared something halal as haram and swore not to do it, you should break that oath and give expiation. Feed ten poor people, clothe ten poor people, or fast for three days if unable to do the others.