Translation
(20) The Chapters on Legal Punishments
كتاب الحدود
(11) Chapter: One Who Commits Immoral Actions Openly
(11.00) باب مَنْ أَظْهَرَ الْفَاحِشَةَ
Sunan Ibn Majah 2560 
It was narrated that Qasim bin Muhammad said:
“Ibn `Abbas mentioned two people who had engaged in the process of Li`an. Ibn Shaddad said to him: 'Is this the one of whom the Messenger of Allah (ﷺ) said: “If I were to stone anyone without proof I would have stoned so-and-so.” Ibn`Abbas said: 'No, that was a woman who, (although she was a Muslim), used to expose herself.'”
حَدَّثَنَا أَبُو بَكْرِ بْنُ خَلاَّدٍ الْبَاهِلِيُّ، حَدَّثَنَا سُفْيَانُ، عَنْ أَبِي الزِّنَادِ، عَنِ الْقَاسِمِ بْنِ مُحَمَّدٍ، قَالَ ذَكَرَ ابْنُ عَبَّاسٍ الْمُتَلاَعِنَيْنِ ‏.‏ فَقَالَ لَهُ ابْنُ شَدَّادٍ هِيَ الَّتِي قَالَ لَهَا رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ لَوْ كُنْتُ رَاجِمًا أَحَدًا بِغَيْرِ بَيِّنَةٍ لَرَجَمْتُهَا ‏"‏ ‏.‏ فَقَالَ ابْنُ عَبَّاسٍ تِلْكَ امْرَأَةٌ أَعْلَنَتْ ‏.‏
Grade :  Sahih (Darussalam)
Reference : Sunan Ibn Majah 2560
In-book reference : Book 20, Hadith 28
English translation : Vol. 3, Book 20, Hadith 2560