When Qabeel -la killed Habeel -as , Adam -as was aggrieved upon Habeel -as with such grief that he -as cut off from the women. So, he -as remained without union with Hawwa -as for five hundred years. Then his -as grief which was with him -as subsided, so he ‑as had union with Hawwa -as , and Allah -azwj Granted to him -as , one thing, and there was no second along with it (single birth, not twins).
وَ اسْمُ شَيْثٍ هِبَةُ اللَّهِ وَ هُوَ أَوَّلُ مَنْ أُوصِيَ إِلَيْهِ مِنَ الْآدَمِيِّينَ فِي الْأَرْضِ ثُمَّ وُلِدَ لَهُ مِنْ بَعْدِ شَيْثٍ يَافِثُ لَيْسَ مَعَهُ ثَانٍ فَلَمَّا أَدْرَكَا وَ أَرَادَ اللَّهُ عَزَّ وَ جَلَّ أَنْ يُبْلِغَ بِالنَّسْلِ مَا تَرَوْنَ وَ أَنْ يَكُونَ مَا قَدْ جَرَى بِهِ الْقَلَمُ مِنْ تَحْرِيمِ مَا حَرَّمَ اللَّهُ عَزَّ وَ جَلَّ مِنَ الْأَخَوَاتِ عَلَى الْإِخْوَةِ أَنْزَلَ بَعْدَ الْعَصْرِ فِي يَوْمِ الْخَمِيسِ حَوْرَاءَ مِنَ الْجَنَّةِ اسْمُهَا نَزْلَةُ ‘And the name of Shees -as was Hibtallah -as , and he -as was the first one, among the humans, who was bequeathed in the earth (as a successor -as (Imam) to a Prophet -as ).
[12] Then there was born unto him -as Yafas -as , not having a second (twin brother or sister) with him -as . So, when they became aware (adults), Allah -azwj Intended that their offspring reach what you are seeing (today), and since the Pen had flowed from Prohibiting what Allah -azwj had Prohibited, from the (marriage of) sisters upon the brothers, after some time, on the Day of Thursday, Caused a Hourie to descend from the Paradise, her name being Nazalat.