Is it permissible to complete the fast of Ashura for one who had intercourse after the Fajradhan and before the Iqama?

If a man has intercourse with his wife intentionally after dawn breaks, while he intended to fast, his fast is not valid. It is recommended for him to abstain from food and drink for the rest of the day and to make up for that day, based on what was narrated by Ar-Rabi' bint Mu'awwidh and 'Abdur-Rahman ibn Maslamah. However, if he had intercourse out of forgetfulness that he was fasting, or thinking that it was still night and it did not become clear to him that the intercourse occurred after dawn, then his fast is valid and there is nothing upon him. This is similar to someone who eats or drinks out of forgetfulness.