"I heard my grandmother say: 'I heard the Messenger of Allah say, during the Farewell Pilgrimage: If an Ethiopian slave is appointed over you who rules according to the Book of Allah, then listen to him and obey."' (Using translation from Nasāʾī 4192)   

سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ وَلَوْ اسْتُعْمِلَ عَلَيْكُمْ عَبْدٌ يَقُودُكُمْ بِكِتَابِ اللهِ ﷻ فَاسْمَعُوا لَهُ وَأَطِيعُوا  

[Machine] I heard the Messenger of Allah ﷺ saying, "May Allah show mercy to those who shave their heads." They said, "What about those who trim their hair?" He said, "May Allah show mercy to those who trim their hair as well."  

سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ يَرْحَمُ اللهُ الْمُحَلِّقِينَ قَالُوا فِي الثَّالِثَةِ وَالْمُقَصِّرِينَ قَالَ وَالْمُقَصِّرِينَ