(1) Whoever harms (others without right), Allah will harm him

بسم الله الرحمن الرحيم

In The Name of Allah, The Most Merciful, The Bestower of Mercy

The Messenger, peace and blessings of Allah be upon him, said:

“Whoever harms (others), Allah will harm him, and whoever places hardship [shows opposition or enmity without right (1)], Allah will show hostility to him”.

“Whoever harms”, meaning, whoever brings about harm to a Muslim or a Mu’aahid, rather, even to a protected animal without right, “Allah will harm him”. Allah will send severe harm upon him—whether in this world, the Hereafter, or in one of them.

“And whoever causes hardship”, or brings about hardship without right, “Allah will place hardship on him” as recompense for what he has done, for indeed, Allah has forbidden His servants from harming or placing hardship on others, rather, he commanded the opposite of that. The best of people are those who are best toward others, and the most beloved of Allah’s servants are those who are most beneficial to His servants.” (2)

Also read here:

الشيخ محمد بن صالح العثيمين-بلوغ المرام-12-5
https://www.alathar.net/home/esound/index.php?op=codevi&coid=32170

(1) Mirqat Al-Mafasteeh (8/ 3156

(2) at-Tanweer Sharḥ al-Jaami As-Ṣagheer 10/298