The Book on Government
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَابْنُ، نُمَيْرٍ قَالاَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ إِدْرِيسَ، ح وَحَدَّثَنَا رِفَاعَةُ بْنُ الْهَيْثَمِ، حَدَّثَنَا خَالِدٌ، - يَعْنِي الطَّحَّانَ - كِلاَهُمَا يَقُولُ عَنْ حُصَيْنٍ، عَنْ سَالِمِ بْنِ أَبِي الْجَعْدِ، عَنْ جَابِرٍ، قَالَ لَوْ كُنَّا مِائَةَ أَلْفٍ لَكَفَانَا كُنَّا خَمْسَ عَشْرَةَ مِائَةً .It has been narrated on the authority of Jabir who said:If we had been a hundred thousand in number, it (the water) would have sufficed us, but actually we were fifteen hundred
From Sahih Muslim, whose reports the scholars accept as authentic.