The Prophet ﷺ saw a boy whose head had been partly shaved while the rest was left unshaven. He forbade this and said, "Shave all of it or leave all of it."
أخبرنا إسحق بن إبراهيم أنبأنا عبد الرزاق قال أنبأنا معمر عن أيوب عن نافع
أن النبي ﷺ رأى صبيا حلق بعض رأسه وترك بعضا فنهى عن ذلك وقال احلقوه كله أو اتركوه كله
Muslim narrated it in the Book of Clothing, chapter on the dislike of shaving part of the head while leaving other parts unshaved, hadith no. 2120, from the hadith of Abdulrazzaq through this same chain. It is also found in Kubra, hadith no. 9296.