The Messenger of Allah ﷺ forbade qaza'. Qaza' means having part of a boy's head shaved and leaving part unshaven.  

نَهَى رَسُولُ اللَّهِ ﷺ عَنِ الْقَزَعِ وَالْقَزَعُ أَنْ يُحْلَقَ رَأْسُ الصَّبِيِّ فَيُتْرَكَ بَعْضُ شَعْرِهِ  

the Prophet ﷺ forbade qaza' which means that the head of a boy is shaved and a lock is left.  

أَنَّ النَّبِيَّ ﷺ نَهَى عَنِ الْقَزَعِ وَهُوَ أَنْ يُحْلَقَ رَأْسُ الصَّبِيِّ فَتُتْرَكَ لَهُ ذُؤَابَةٌ  

The Prophet ﷺ saw a boy with part of his head shaved and part left unshaven. He forbade them to do that, saying: Shave it all or leave it all.  

أَنَّ النَّبِيَّ ﷺ رَأَى صَبِيًّا قَدْ حُلِقَ بَعْضُ شَعْرِهِ وَتُرِكَ بَعْضُهُ فَنَهَاهُمْ عَنْ ذَلِكَ وَقَالَ احْلِقُوهُ كُلَّهُ أَوِ اتْرُكُوهُ كُلَّهُ