The Prophet ﷺ said: If anyone finds an animal whose owners were helpless to provide fodder to it and so they turned it out (of their house), and he took it and looked after it, it will belong to him. Abu Dawud said: This is the tradition of Hammad. It is more plain and perfect.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ مَنْ وَجَدَ دَابَّةً قَدْ عَجَزَ عَنْهَا أَهْلُهَا أَنْ يَعْلِفُوهَا فَسَيَّبُوهَا فَأَخَذَهَا فَأَحْيَاهَا فَهِيَ لَهُ قَالَ فِي حَدِيثِ أَبَانَ قَالَ عُبَيْدُ اللَّهِ فَقُلْتُ عَمَّنْ قَالَ عَنْ غَيْرِ وَاحِدٍ مِنْ أَصْحَابِ النَّبِيِّ ﷺ  

The Prophet ﷺ said: If anyone leaves an animal at a place of perishing and another man brings it to life, it belongs to him who brings it to life.  

عَنِ الشَّعْبِيِّ يَرْفَعُ الْحَدِيثَ إِلَى النَّبِيِّ ﷺ أَنَّهُ قَالَ مَنْ تَرَكَ دَابَّةً بِمُهْلِكٍ فَأَحْيَاهَا رَجُلٌ فَهِيَ لِمَنْ أَحْيَاهَا