It has been narrated on the authority of Umar, who said:

The properties abandoned by Banu Nadir were the ones which Allah bestowed upon His Messenger for which no expedition was undertaken either with cavalry or camelry. These properties were particularly meant for the Prophet (ﷺ). He would meet the annual expenditure of his family from the income thereof, and would spend what remained for purchasing horses and weapons as preparation for Jihad.

حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، وَمُحَمَّدُ بْنُ عَبَّادٍ، وَأَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ - وَاللَّفْظُ لاِبْنِ أَبِي شَيْبَةَ - قَالَ إِسْحَاقُ أَخْبَرَنَا وَقَالَ الآخَرُونَ، حَدَّثَنَا سُفْيَانُ، عَنْ عَمْرٍو، عَنِ الزُّهْرِيِّ، عَنْ مَالِكِ بْنِ أَوْسٍ، عَنْ عُمَرَ، قَالَ كَانَتْ أَمْوَالُ بَنِي النَّضِيرِ مِمَّا أَفَاءَ اللَّهُ عَلَى رَسُولِهِ مِمَّا لَمْ يُوجِفْ عَلَيْهِ الْمُسْلِمُونَ بِخَيْلٍ وَلاَ رِكَابٍ فَكَانَتْ لِلنَّبِيِّ صلى الله عليه وسلم خَاصَّةً فَكَانَ يُنْفِقُ عَلَى أَهْلِهِ نَفَقَةَ سَنَةٍ وَمَا بَقِيَ يَجْعَلُهُ فِي الْكُرَاعِ وَالسِّلاَحِ عُدَّةً فِي سَبِيلِ اللَّهِ ‏.‏