"Am I sinful if I had intercourse with my wife before dawn and ejaculated during the Adhan, knowing that I heard it is permissible to complete intercourse even with the Adhan? "

The ruling for someone who hears the adhan during intercourse: If it is not in Ramadan, they are not required to stop the intercourse. However, if it is during Ramadan, and they continue the intercourse after hearing the Fajr adhan and knowing that dawn has broken, their fast is invalidated, and they must make up the fast as well as offer expiation. But if they were ignorant or mistakenly believed that they could continue, they only need to make up the fast without offering expiation. After finishing, they must purify themselves and strive to join the congregational prayer, and if they are unable to join, they pray with their family.