Messenger of Allah ﷺ said, "While a man was walking on a road. he became very thirsty. Then he came across a well, got down into it, drank (of its water) and then came out. Meanwhile he saw a dog panting and licking mud because of excessive thirst. The man said to himself "This dog is suffering from the same state of thirst as I did." So he went down the well (again) and filled his shoe (with water) and held it in his mouth and watered the dog. Allah thanked him for that deed and forgave him." The people asked, "O Messenger of Allah ﷺ! Is there a reward for us in serving the animals?" He said, "(Yes) There is a reward for serving any animate (living being) ." (Using translation from Bukhārī 6009)
قَالَ رَسُولُ اللهِ ﷺ بَيْنَا رَجُلٌ يَمْشِي وَهُوَ بِطَرِيقٍ إِذِ اشْتَدَّ عَلَيْهِ الْعَطَشُ فَوَجَدَ بِئْرًا فَنَزَلَ فِيهَا فَشَرِبَ ثُمَّ خَرَجَ فَإِذَا كَلْبٌ يَلْهَثُ يَأْكُلُ الثَّرَى مِنَ الْعَطَشِ فَقَالَ لَقَدْ بَلَغَ هَذَا الْكَلْبَ مِنَ الْعَطَشِ مِثْلُ الَّذِي بَلَغَنِي فَنَزَلَ الْبِئْرَ فَمَلَأَ خُفَّهُ مَاءً ثُمَّ أَمْسَكَهُ بِفِيهِ حَتَّى رَقِيَ بِهِ فَسَقَى الْكَلْبَ فَشَكَرَ اللهُ لَهُ فَغَفَرَ لَهُ قَالُوا يَا رَسُولَ اللهِ وَإِنَّ لَنَا فِي الْبَهَائِمِ لَأَجْرًا؟ فَقَالَ رَسُولُ اللهِ ﷺ فِي كُلِّ ذَاتِ كَبِدٍ رَطْبَةٍ أَجْرٌ