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