Sulaiman b. Yasar, the freed slave of Maimuna, the wife of Allah's Apostle ﷺ, narrated from one of the Ansari Companions of Messenger of Allah ﷺ that Messenger of Allah ﷺ retained (the practice) of Qasama as it was in the pre-Islamic days.  

أَخْبَرَنِي أَبُو سَلَمَةَ بْنُ عَبْدِ الرَّحْمَنِ وَسُلَيْمَانُ بْنُ يَسَارٍ مَوْلَى مَيْمُونَةَ زَوْجِ النَّبِيِّ ﷺ عَنْ رَجُلٍ مِنْ أَصْحَابِ رَسُولِ اللَّهِ ﷺ مِنَ الأَنْصَارِ أَنَّ رَسُولَ اللَّهِ ﷺ أَقَرَّ الْقَسَامَةَ عَلَى مَا كَانَتْ عَلَيْهِ فِي الْجَاهِلِيَّةِ  

[Machine] From some of the companions of the Prophet ﷺ from the Ansar, it is narrated that the Messenger of Allah ﷺ confirmed her (i.e. a woman) on what she was upon during the pre-Islamic era and ruled by her when some of the Ansar disputed regarding a killing they claimed against the Jews.  

عَنْ رِجَالٍ مِنْ أَصْحَابِ النَّبِيِّ ﷺ مِنَ الْأَنْصَارِ أَنَّ رَسُولَ اللهِ ﷺ أَقَرَّهَا عَلَى مَا كَانَتْ عَلَيْهِ فِي الْجَاهِلِيَّةِ وَقَضَى بِهَا بَيْنَ نَاسٍ مِنَ الْأَنْصَارِ فِي قَتِيلٍ ادَّعَوْهُ عَلَى الْيَهُودِ  

the Messenger or Allah approved of Qasamah as it had been during the Jahiliyyah. (Using translation from Nasāʾī 4707)   

عَنْ رَجُلٍ مِنْ أَصْحَابِ رَسُولِ اللهِ ﷺ مِنَ الْأَنْصَارِ أَنَّ رَسُولَ اللهِ ﷺ «أَقَرَّ الْقَسَامَةَ عَلَى مَا كَانَتْ عَلَيْهِ فِي الْجَاهِلِيَّةِ» وَاللَّفْظُ لِأَحْمَدَ