Sunan Ibn Majah
3637
Sahih+3

It was narrated from Nafi’ that Ibn ‘Umar said:“The Messenger of Allah (ﷺ) forbade Qaza’.” He (Nafi’) said: “What is Qaza’?” He said: “It means shaving part of a child’s head and leaving another part.”

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi