Perhaps he (the man accompanying her) intends to cohabit with her. They said: Yes. Thereupon Messenger of Allah ﷺ said: I have decided to curse him with such a curse as may go along with him to his grave. How can he own him (the child to be born) and that is not lawful for him, and how can he take him as a servant for that is not lawful for him?  

عَنِ النَّبِيِّ ﷺ أَنَّهُ أَتَى بِامْرَأَةٍ مُجِحٍّ عَلَى بَابِ فُسْطَاطٍ فَقَالَ لَعَلَّهُ يُرِيدُ أَنْ يُلِمَّ بِهَا فَقَالُوا نَعَمْ فَقَالَ رَسُولُ اللَّهِ ﷺ لَقَدْ هَمَمْتُ أَنْ أَلْعَنَهُ لَعْنًا يَدْخُلُ مَعَهُ قَبْرَهُ كَيْفَ يُوَرِّثُهُ وَهُوَ لاَ يَحِلُّ لَهُ كَيْفَ يَسْتَخْدِمُهُ وَهُوَ لاَ يَحِلُّ لَهُ  

A hadith like this has been transmitted on the authority of Shu'ba.  

عَنْ شُعْبَةَ فِي هَذَا الإِسْنَادِ