Hadithcore
Sahih Muslim, 1856 g
sahih

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.

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 ‏.‏

References2 variants
In-Book Reference
Book 33, Hadith 110
USC-MSA web (English) reference
Book 20, Hadith 4582 (deprecated numbering scheme)