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.
suyuti:2364a

when anyone sits between the four parts of a woman and the parts (of the male and female) which are circumscised join together, then bath becomes obligatory. (Using translation from Abū Dāʾūd 216)   

السيوطي:٢٣٦٤a

"إِذا قَعَد بين شُعَبها الأرْبَع وألزَق الخِتانَ بالخِتْانِ فقد وَجَبَ الغُسْلُ" .  

[حم] أحمد عبد الرزاق عن عائشة، [د] أبو داود عن أبي هريرة

See similar narrations below:

Collected by Abū Dāwūd, Aḥmad, Suyūṭī
abudawud:216Muslim b. Ibrāhīm al-Farāhīdī > Hishām And Shuʿbah > Qatādah > al-Ḥasan > Abū Rāfiʿ > Abū Hurayrah

when anyone sits between the four parts of a woman and the parts (of the male and female) which are circumscised join together, then bath becomes obligatory.  

أبو داود:٢١٦حَدَّثَنَا مُسْلِمُ بْنُ إِبْرَاهِيمَ الْفَرَاهِيدِيُّ حَدَّثَنَا هِشَامٌ وَشُعْبَةُ عَنْ قَتَادَةَ عَنِ الْحَسَنِ عَنْ أَبِي رَافِعٍ عَنْ أَبِي هُرَيْرَةَ

أَنَّ النَّبِيَّ ﷺ قَالَ إِذَا قَعَدَ بَيْنَ شُعَبِهَا الأَرْبَعِ وَأَلْزَقَ الْخِتَانَ بِالْخِتَانِ فَقَدْ وَجَبَ الْغُسْلُ  

ahmad:24817Abū Nuʿaym > Sufyān > ʿAlī b. Zayd > Saʿīd b. al-Musayyib > ʿĀʾishah

[Machine] "The Messenger of Allah ﷺ said, 'If one sits among a gathering of people and his circumcised area touches the circumcised area of another person, then it becomes obligatory to perform ritual washing.'"  

أحمد:٢٤٨١٧حَدَّثَنَا أَبُو نُعَيْمٍ قَالَ حَدَّثَنَا سُفْيَانُ عَنْ عَلِيِّ بْنِ زَيْدٍ عَنْ سَعِيدِ بْنِ الْمُسَيِّبِ عَنْ عَائِشَةَ قَالَتْ

قَالَ رَسُولُ اللهِ ﷺ إِذَا جَلَسَ بَيْنَ الشُّعَبِ الْأَرْبَعِ ثُمَّ أَلْزَقَ الْخِتَانَ بِالْخِتَانِ فَقَدْ وَجَبَ الْغُسْلُ  

ahmad:24206Ismāʿīl > ʿAlī b. Zayd > Saʿīd b. al-Musayyib > ʿĀʾishah

[Machine] The Messenger of Allah ﷺ said, "If a person sits between the four limbs [i.e., the thighs] and their circumcised part touches the circumcised part, then Ghusl (ritual bath) becomes obligatory."  

أحمد:٢٤٢٠٦أَخْبَرَنَا إِسْمَاعِيلُ قَالَ أَخْبَرَنَا عَلِيُّ بْنُ زَيْدٍ عَنْ سَعِيدِ بْنِ الْمُسَيِّبِ عَنْ عَائِشَةَ قَالَتْ

قَالَ رَسُولُ اللهِ ﷺ إِذَا قَعَدَ بَيْنَ الشُّعَبِ الْأَرْبَعِ ثُمَّ أَلْزَقَ الْخِتَانَ بِالْخِتَانِ فَقَدْ وَجَبَ الْغُسْلُ