There is no Kaffarah but she has to repent and ask Allah for forgiveness. This is providing that she was certain and sure that she had her period. But if she was in doubt and had no room to confirm this, she didn’t do anything wrong.
There is no Kaffarah but she has to repent and ask Allah for forgiveness. This is providing that she was certain and sure that she had her period. But if she was in doubt and had no room to confirm this, she didn’t do anything wrong.