Mishkat al-Masabih 19 Jihad كتاب الجهاد 173

وَعَنْ سَلَمَةَ بْنِ الْأَكْوَعِ قَالَ أَتَى النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَيْنٌ مِنَ الْمُشْرِكِينَ وَهُوَ فِي سَفَرٍ فَجَلَسَ عِنْدَ أَصْحَابِهِ يَتَحَدَّثُ ثُمَّ انْفَتَلَ فَقَالَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «اطْلُبُوهُ وَاقْتُلُوهُ» . فَقَتَلْتُهُ فنفَّلَني سلبَه

Salama b. al-Akwa‘ said: A spy of the polytheists who came to the Prophet when he was on a journey sat and talked with his companions and afterwards withdrew. The Prophet then said, “Look for him and kill him,” so I killed him and the Prophet gave me the spoil taken from him. (Bukhari and Muslim.)