Hadith: Verily, Allah tortures those who torture people in this world

عن هشام بن حكيم بن حزام رضي الله عنهما : أنه مَرَّ بالشَّام على أُناس من الأَنْبَاطِ، وقد أُقيموا في الشمس، وصُبَّ على رؤوسهم الزَّيْتُ! فقال: ما هذا؟ قيل: يُعَذَّبُون في الخَرَاج - وفي رواية: حُبِسُوا في الجِزْيَةِ - فقال هشام: أشْهَدُ لسَمِعْتُ رسول الله صلى الله عليه وسلم يقول: «إن الله يُعَذِّب الَّذِينَ يُعَذِّبُونَ الناس في الدنيا». فدخل على الأمير، فحدثه، فأمر بهم فَخُلُّوا.
[صحيح] - [رواه مسلم]

Hishām ibn Hakīm ibn Hizām (may Allah be pleased with him) reported that while in the Levant he passed by some Nabataean peasants who had been made to stand in the sun with oil poured on their heads. He asked, "What is this?" He was told, "They are being punished on account of the land-tax." In another narration, "They have been imprisoned on account of the Jizyah." So Hishām said: "I testify that I heard the Messenger of Allah (may Allah's peace and blessings be upon him) saying: 'Verily, Allah tortures those who torture people in this world.'" He then went to the ruler and spoke with him, and the ruler ordered their release.
Sahih/Authentic. - [Muslim]

Explanation

Hishām ibn Hakīm ibn Hizām (may Allah be pleased with him) was in the Levant and passed by some non-Arab peasants who were made to stand in the sun in order to be burnt by it. Their torture was amplified by pouring oil over their heads, because its heat intensifies with the heat of the sun. Hishām,(may Allah be pleased with him) asked about the reason for their torture, and he was told that they did not pay their land tax (Kharāj). Another narration says that they did not pay the Jizyah (head tax). When Hishām,(may Allah be pleased with him) witnessed such torture of those weak individuals, he said: I testify that I heard the Messenger of Allah (may Allah's peace and blessings be upon him) say that whoever tortures people who do not deserve to be tortured, Allah, the Exalted, will torture him on the Day of Resurrection. After he made this statement, he went to the ruler of the land and informed him of what he had heard from the Messenger of Allah (may Allah's peace and blessings be upon him). The ruler immediately set them free. However, this does not mean that the wrong-doer should not be punished with what is likely to deter him and put an end to his evil; rather, what is forbidden is torture that exceeds the customary forms of punishment.