Abdullah ibn AbuBakr and some children of Muhammad ibn Maslamah said: There remained some people of Khaybar and they confined themselves to the fortresses. They asked the Messenger of Allah ﷺ to protect their lives and let them go. He did so. The people of Fadak heard this; they also adopted a similar way. (Fadak) was, therefore, exclusively reserved for the Messenger of Allah ﷺ, for it was not captured by the expedition of cavalry and camelry. (Using translation from Abū Dāʾūd 3016)   

عَنِ الزُّهْرِيِّ وَعَبْدِ اللهِ بْنِ أَبِي بَكْرٍ وَبَعْضِ وَلَدِ مُحَمَّدِ بْنِ مَسْلَمَةَ قَالُوا بَقِيَتْ بَقِيَةٌ مِنْ أَهْلِ خَيْبَرَ فَحَصَّنُوا فَسَأَلُوا رَسُولَ اللهِ ﷺ أَنْ تُحْقَنَ دِمَاؤُهُمْ وَيُسَيِّرَهُمْ فَفَعَلَ فَسَمِعَ بِذَلِكَ أَهْلُ فَدَكٍ فَنَزَلُوا عَلَى مِثْلِهِ فَكَانَتْ لِرَسُولِ اللهِ ﷺ خَالِصَةً؛ لِأَنَّهُ لَمْ يُوجَفْ عَلَيْهَا بِخَيْلٍ وَلَا رِكَابٍ