It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) forbade «قزع», and the meaning of «قزع» is that when shaving a child's hair, some of the hair is cut and some is left.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 4973