One of the most important rights that belong to animals is that they are entitled to our good treatment. Allah rewards our acts of charity that we do for any living creature, all human and animals included. In fact, Allah appreciates mercy, kindness, and empathy for the animals so much that it can result in the forgiveness of our sins.
بَيْنَمَا رَجُلٌ يَمْشِي بِطَرِيقٍ اشْتَدَّ عَلَيْهِ الْعَطَشُ فَوَجَدَ بِئْرًا فَنَزَلَ فِيهَا فَشَرِبَ ثُمَّ خَرَجَ فَإِذَا كَلْبٌ يَلْهَثُ يَأْكُلُ الثَّرَى مِنْ الْعَطَشِ فَقَالَ الرَّجُلُ لَقَدْ بَلَغَ هَذَا الْكَلْبَ مِنْ الْعَطَشِ مِثْلُ الَّذِي كَانَ بَلَغَ مِنِّي فَنَزَلَ الْبِئْرَ فَمَلَأَ خُفَّهُ مَاءً ثُمَّ أَمْسَكَهُ بِفِيهِ حَتَّى رَقِيَ فَسَقَى الْكَلْبَ فَشَكَرَ اللَّهُ لَهُ فَغَفَرَ لَهُ
Once a man suffered from thirst while he was walking on a journey. When he found a well, he climbed down into it and drank from it. Then he came out and saw a dog lolling its tongue from thirst and licking the ground. The man said: This dog has suffered thirst just as I have suffered from it. He climbed down into the well, filled his shoe with water, and caught it in his mouth as he climbed up. Then he gave the dog a drink. Allah appreciated this deed, so he forgave him.
It was said, “O Messenger of Allah, is there a reward for charity even for the animals?”
The Prophet(saw) said: فِي كُلِّ كَبِدٍ رَطْبَةٍ أَجْرٌ
In every living being there is a reward for charity.
Source: Ṣaḥīḥ al-Bukhārī 5663, Grade: Muttafaqun Alayhi
This great reward for charity to animals will apply to any animal regardless of whether they are officially under our care or not.
Suraqa ibn Ju’shum reported: I asked the Prophet about a lost camel that comes to drink from my cisterns I have prepared for my own camels, “Will I be rewarded if I give it some water to drink?” The Prophet(saw) said:
نَعَمْ فِي كُلِّ ذَاتِ كَبِدٍ حَرَّى أَجْرٌ
Yes, in every living being there is a reward for charity.
Source: Sunan Ibn Mājah 3686, Grade: Sahih
We have to be gentle with the animals even when we have to discipline them. Sometimes it is necessary to strike the animal lightly in order to train it in some task, but we should only do so to the minimum extent needed and never harm the animal in the process.
Aisha reported: I was upon a camel that was misbehaving, so I started to beat it. The Messenger of Allah, peace and blessings be upon him, said to me:
عَلَيْكِ بِالرِّفْقِ فَإِنَّ الرِّفْقَ لَا يَكُونُ فِي شَيْءٍ إِلَّا زَانَهُ وَلَا يُنْزَعُ مِنْ شَيْءٍ إِلَّا شَانَهُ
You must be gentle. Verily, gentleness is not in anything except that it beautifies it, and it is not removed from anything except that it disgraces it.
Source: Musnad Aḥmad 24417, Grade: Sahih
Killing an animal for no beneficial reason or behaving in a cruel manner is a major sin and a violation of the rights conferred upon them by Allah. Even the small birds that are killed unjustly will come pleading for justice on the Day of Judgement.
Abdullah ibn Umar reported: The Messenger of Allah, peace and blessings be upon him, said:
مَنْ قَتَلَ عُصْفُورًا فَمَا فَوْقَهَا بِغَيْرِ حَقِّهَا سَأَلَ اللَّهُ عَزَّ وَجَلَّ عَنْهَا يَوْمَ الْقِيَامَةِ
If someone kills so much as a sparrow or anything larger without a just cause, then Allah the Exalted will ask him about it on the Day of Resurrection.
Source: Sunan al-Nasā’ī 4445, Grade: Sahih