Narrated 'Abdullah bin 'Amr bin al-'Aar (RA):

The Prophet (ﷺ) commanded him to equip an army. Then, when the camels were insufficient, he commanded him to keep back the young camels of Sadaqah. He said, "I was taking a camel to be replaced by two when the camels of Sadaqah came." [Reported by al-Hakim and al-Baihaqi; its narrators are reliable].

وَعَنْ عَبْدِ اَللَّهِ بْنِ عَمْرٍو ‏-رَضِيَ اَللَّهُ عَنْهُمَا‏-; { أَنَّ رَسُولَ ‏- صلى الله عليه وسلم ‏-أَمَرَهُ أَنْ يُجَهِّزَ جَيْشًا فَنَفِدَتْ اَلْإِبِلُ، فَأَمَرَهُ أَنْ يَأْخُذَ عَلَى قَلَائِصِ اَلصَّدَقَةِ.‏ قَالَ: فَكُنْتُ آخُذُ اَلْبَعِيرَ بِالْبَعِيرَيْنِ إِلَى إِبِلِ اَلصَّدَقَةِ } رَوَاهُ اَلْحَاكِمُ وَالْبَيْهَقِيُّ, وَرِجَالُهُ ثِقَاتٌ [1]‏ .‏