I commanded you to burn so-and-so and so-and-so, but no one punishes with fire except Allah. So if you find them, kill them
Authentic hadithعن أبي هريرة رضي الله عنه قال: بَعَثَنَا رسول الله صلى الله عليه وسلم في بَعْثٍ، فقال: «إن وجَدْتُم فُلانا وفُلانا» لرجلين من قُرَيْش سَمَّاهُما «فأَحْرِقُوهُمَا بالنَّار» ثم قال رسول الله صلى الله عليه وسلم حين أردنا الخروج: «إني كنت أَمَرْتُكُمْ أن تُحْرِقُوا فلانًا وفلانًا، وإن النَّار لا يُعَذِّبُ بها إلا الله، فإن وجَدْتُمُوهُما فاقْتُلُوهُما».
Abu Hurayrah (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) sent us out on an expedition and said: "If you find so-and-so and so-and-so", referring to two men from Quraysh whom he named, "then burn them with fire." Then, when we were set to go out, the Messenger of Allah (may Allah's peace and blessings be upon him) said: "I commanded you to burn so-and-so and so-and-so, but no one punishes with fire except Allah. So if you find them, kill them."
Explanation
In this Hadīth, Abu Hurayrah (may Allah be pleased with him) tells that the Messenger of Allah (may Allah's peace and blessings be upon him) sent them out in an army to fight the enemy. He ordered them to burn two individuals from Quraysh, whom he named, whenever they spot them. Then he said to them when they came to bid him farewell before their journey: I commanded you to burn so-and-so and so-and-so, but no one punishes with fire except Allah, so when you seize them, kill them.
Source · Narrated by Bukhari
From the Hadith Encyclopedia (hadeethenc.com).