Bukhari

Hadith Commentary:
1.
From one narration, it is understood that the person who gave water to the thirsty dog belonged to the Children of Israel (Bani Isra'il). Also, a similar incident regarding a sinful woman from the Children of Israel is mentioned in the hadiths; she too gave water to a thirsty dog using her sock.
(Sahih al-Bukhari, Book of the Beginning of Creation, Hadith: 3321 and Stories of the Prophets, Hadith: 3467)
From this hadith, it is inferred that the leftover water from a dog is not impure (najis), but this inference is weak for several reasons.
(a)
It is possible that she took the water out of her sock and poured it into another vessel or into a hole in the ground and then gave it to the dog.
(b)
It is possible that she gave water to the dog directly from her sock and then washed it.
(c)
It is also possible that she considered the sock impure and threw it away, never using it again.
With all these possibilities present, the aforementioned inference is not correct.
(d)
Furthermore, the incidents of previous nations are not a binding proof for us.
Can the partial action of a single person be given decisive authority in the matter of purity and impurity? At most, it can be understood from this that showing compassion to Allah’s creation is a cause for forgiveness with Allah.
(Fath al-Bari: 1/364)
2.
In one narration, when the Messenger of Allah (sallallahu alayhi wa sallam) related this incident, the noble Companions (radi Allahu anhum) said:
“Will we also receive reward for showing kindness to animals?” He replied:
“There is a reward for you in (showing kindness to) every living creature with a moist liver.”
(Sahih al-Bukhari, Book of Oppressions, Hadith: 2466)
In our Shari’ah, those animals are worthy of respect which are not harmful to others.
(Fath al-Bari: 5/53)
3.
The following benefits are derived from this hadith:
(a)
A person may travel alone and without provisions,
provided that there is no fear of danger in traveling in this manner.
(b)
The importance of showing kindness to people is evident, because if forgiveness was granted for giving water to a dog, then showing compassion to humans is of even greater importance.
(c)
If there is no deserving Muslim present for voluntary charity (nafl sadaqah), then charity and alms may be given to polytheists (mushrikeen).
Similarly, if both a human and an animal are equally in need and only one can be helped, then the human is more worthy of respect than animals and should be helped.
(Fath al-Bari: 5/53)