Narrated Abu Musa: The Prophet (ﷺ) said, "I saw in a dream that I moved a sword and its blade got broken, and that symbolized the casualties which the believers suffered on the day of Uhud. Then I moved it again, and it became as perfect as it had been, and that symbolized the Conquest (of Mecca) which Allah helped us to achieve, and the union of all the believers. I (also) saw cows in the dream, and what Allah does is always beneficial. Those cows appeared to symbolize the faithful believers (who were martyred) on the day of Uhud."
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مُحَمَّدُ بْنُ الْعَلاَءِ، حَدَّثَنَا أَبُو أُسَامَةَ، عَنْ بُرَيْدِ بْنِ عَبْدِ اللَّهِ بْنِ أَبِي بُرْدَةَ، عَنْ جَدِّهِ أَبِي بُرْدَةَ، عَنْ أَبِي مُوسَى ـ رضى الله عنه ـ أُرَى عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " رَأَيْتُ فِي رُؤْيَاىَ أَنِّي هَزَزْتُ سَيْفًا فَانْقَطَعَ صَدْرُهُ، فَإِذَا هُوَ مَا أُصِيبَ مِنَ الْمُؤْمِنِينَ يَوْمَ أُحُدٍ، ثُمَّ هَزَزْتُهُ أُخْرَى فَعَادَ أَحْسَنَ مَا كَانَ، فَإِذَا هُوَ مَا جَاءَ بِهِ اللَّهُ مِنَ الْفَتْحِ وَاجْتِمَاعِ الْمُؤْمِنِينَ، وَرَأَيْتُ فِيهَا بَقَرًا وَاللَّهُ خَيْرٌ، فَإِذَا هُمُ الْمُؤْمِنُونَ يَوْمَ أُحُدٍ ".
sunnah.com