Hadithcore
Sahih Muslim, 1935 c
sahih

'Amr reported on the authority of Jabir that in the expedition of Khabat (leaves) a person slaughtered three camels, then three, then three, then Abu 'Ubaida forbade him (to do so fearing that the rides may become short).

وَحَدَّثَنَا عَبْدُ الْجَبَّارِ بْنُ الْعَلاَءِ، حَدَّثَنَا سُفْيَانُ، قَالَ سَمِعَ عَمْرٌو، جَابِرًا يَقُولُ فِي جَيْشِ الْخَبَطِ إِنَّ رَجُلاً نَحَرَ ثَلاَثَ جَزَائِرَ ثُمَّ ثَلاَثًا ثُمَّ ثَلاَثًا ثُمَّ نَهَاهُ أَبُو عُبَيْدَةَ ‏.‏

References2 variants
In-Book Reference
Book 34, Hadith 29
USC-MSA web (English) reference
Book 21, Hadith 4758 (deprecated numbering scheme)