I heard Usama bin Sharik saying: I came to the Prophet ﷺ, and his companions we as if they birds were perched on their heads (i.e. they were still and attentive).  

سَمِعْتُ أُسَامَةَ بْنَ شَرِيكٍ يَقُولُ «أَتَيْتُ رَسُولَ اللهِ ﷺ فَإِذَا أَصْحَابُهُ عِنْدَهُ كَأَنَّ عَلَى رُءُوسِهِمُ الطَّيْرُ»  

Do not turn unbelievers after me ; one of you may strike the neck of the other. (Using translation from Abū Dāʾūd 4686)   

لِي رَسُولُ اللهِ ﷺ «اسْتَنْصِتِ النَّاسَ» فَقَالَ «لَا تَرْجِعُوا بَعْدِي كُفَّارًا يَضْرِبُ بَعْضُكُمْ رِقَابَ بَعْضٍ»