Fathwa - He had intercourse with his wife thinking that it isthe day of ‘Eed and then found out that it is still Ramadan

Question
In Qatar, we are used to breaking our fast after Ramadan with Saudi
Arabia. However, there was one year in which Saudi Arabia declared'Eed
and I thought that Qatar would also declare it and it is simply a
matter of time. I slept without making the intention to fast, woke up
at dawn and had intercourse with my wife.Then, I discovered that the
people of Qatar considered it a day of Ramadan and they fasted. Should
I offer expiation?
Answer
All perfect praise be to Allaah, The Lord of the worlds. I testify
that there is none worthy of worship except Allaah, and that Muhammad,
is His slave and messenger.
You should have made sure whether this day was 'Eed or not. Since what
happened has happened, you should make up for this day and you are not
obliged to offer any expiation because you did not intend to violate
the sanctity of the month. Expiation is obligatory upon whoever does
so intentionally.
Whoever does this by mistake is not required to offer any expiation as
Allaah The Almighty Says (what means): {Our Lord, do not impose blame
upon us if we have forgotten or erred.} [Quran 2:286]
Allaah The Exalted also Says (what means): {And there is no blame upon
you for that in which youhave erred but [only for] what your hearts
intended.} [Quran 33:5]
Allaah Knows best.