Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
darimi:1136Muḥammad b. ʿĪsá > Hushaym > Mughīrah > Ibrāhīm Wʾkhbrnā Ismāʿīl b. Abū Khālid > ʿĀmir Fīman Atá Ahlah And Hī Ḥāʾiḍ

[Machine] From Aamer regarding someone who had relations with his wife while she was menstruating, they said, "It is a sin that has come upon him. He should seek forgiveness from Allah and repent to Him, and he should not repeat the act."  

الدارمي:١١٣٦أَخْبَرَنَا مُحَمَّدُ بْنُ عِيسَى حَدَّثَنَا هُشَيْمٌ أَنبَأَنَا مُغِيرَةُ عَنْ إِبْرَاهِيمَ وأخْبرنا إِسْمَاعِيلُ بْنُ أَبِي خَالِدٍ

عَنْ عَامِرٍ فِيمَنْ أَتَى أَهْلَهُ وَهِيَ حَائِضٌ قَالَا «ذَنْبٌ أَتَاهُ يَسْتَغْفِرُ اللَّهَ وَيَتُوبُ إِلَيْهِ وَلَا يَعُودُ»