Does the hadith "Whoever has grown hair is to be killed, and whoever has not grown hair is to be left alone," mentioned in the story of Banu Qurayzah, refer to the growth of pubic hair or the beard? And is the hadith of Atiyyah al-Qurazi authentic?

The Hadith (definition) of Aslam al-Ansari is weak. The 'growth' (inbat) referred to in it means coarse pubic hair. Rulings in Sharia (definition) are related to puberty, which is the distinguishing line between an adult and a child, based on the Prophet's (peace be upon him) saying: "The pen is lifted from three..." and he mentioned among them: "a child until he reaches puberty."

The growth of pubic hair is an indicator and sign of puberty, especially concerning disbelievers, because verifying their puberty by questioning them is difficult. Therefore, 'growth' was considered a means to identify the adults among Banu Qurayza to fight them after their great betrayal, as the Prophet (peace be upon him) only killed the adult fighters among them. The prohibition of killing children is a well-established principle in Islam.