Muslims are not allowed to keep another goat standing while a goat is being slaughtered

A Hadith narrated by Ibn Abbas (May Allah be pleased with him) is recorded in Tabarani’s Mustadarak and other books:

Once the Prophet ﷺ was walking on a street. He saw that a person had laid down a goat on the road and put his foot on its throat and was pressing it hard. The goat was being suffocated. While doing this, he was sharpening his knife right in front of the goat. The poor goat could not even run away. The Prophet ﷺ turned to him and said:

“What are you doing? Why did you not sharpen the knife before putting the goat down? The goat is helplessly watching you this while being suffocated. Do you want to give this goat the taste of death twice?”

(He was referring to the torture of the goat the man was giving it). In other traditions, he said, “Do you want to give multiple deaths to this goat?”

Whoever shows mercy upon those who are on earth, the one who is in the Heavens will show mercy upon him

Imam Bukhari narrates in his Sahih al Adab al Mufrad about the virtues of showing mercy towards the animals while slaughtering it. The narrator is Qurra ibn Abi (May Allah be pleased with him). A man said, “I slaughter animals but I show mercy towards the animals, too. I do not sharpen the knife before their eyes. I do not slaughter the animal in front of other animals.” The Prophet ﷺ responded”

“If you are showing mercy upon the animal even while slaughtering it, then Allah will show mercy upon you as well.”

The other hadith says:

“Whoever shows mercy upon those who are on earth, the One who is in the Heavens, will show mercy upon you”.

Allama Hali a popular Urdu poet has turned this hadith into a couplet.

کرو مہربانی تم اہلِ زمین پر

خدا مہربان ہو گا عرشِ بریں پر 

Be kind to those who are on Earth,

Allah would be merciful to you (when He is) on His Throne (on the Day of Judgement)