Sahih Muslim , Book 7, Hadith 3097 (USC-MSA) ⓘ
This hadith has been narrated on the same authority by Ubaidullah. And in the narration of Abu Bakr (the words are): " More than three (days)." Ibn Numair narrated on the authority of his father, (and the words are):" Three (days) except (when) she has a Mahram with her."
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ نُمَيْرٍ، وَأَبُو أُسَامَةَ ح وَحَدَّثَنَا ابْنُ نُمَيْرٍ، حَدَّثَنَا أَبِي جَمِيعًا، عَنْ عُبَيْدِ اللَّهِ، بِهَذَا الإِسْنَادِ . فِي رِوَايَةِ أَبِي بَكْرٍ فَوْقَ ثَلاَثٍ . وَقَالَ ابْنُ نُمَيْرٍ فِي رِوَايَتِهِ عَنْ أَبِيهِ، " ثَلاَثَةً إِلاَّ وَمَعَهَا ذُو مَحْرَمٍ " .
also referenced under: Book 15, Hadith 463 (In-Book) & Hadith 1338 (Reference)