In some personal status laws, they set the age of puberty at eighteen years; what is the guidance on this?

The questioner:
Honorable Shaykh, may Allah grant you success. The questioner says: Yesterday, a personal status law was published in some newspapers, intended for the study of its articles. One of its articles states that the age of puberty is eighteen years.

The Shaykh:
The Shari'ah does not set it at eighteen years. Puberty occurs through signs, not by age alone. Age is the last of the signs. A boy may reach puberty at ten, and a girl may reach it at nine when menstruation begins. Puberty also occurs through the growth of hair around the private parts, the growth of hair around the male private parts, or the growth of a mustache for a male. These are signs of puberty. If none of the signs occur—no menstruation and no hair growth—then the last thing is the age of fifteen. This is what the evidence indicates: fifteen. Yes, the Hanafis say it is eighteen, and the law adopted this, but this is the weaker position. It is fifteen, because Ibn 'Umar came to the Messenger (peace and blessings be upon him) to be permitted to participate in jihad at the Battle of Uhud, but the Messenger (peace and blessings be upon him) did not permit it because he was under fifteen. When the Battle of the Trench came, he came and the Messenger (peace and blessings be upon him) permitted it because he had reached fifteen. Fifteen years old. This is evidence that the age of puberty is fifteen years. Yes. And may Allah preserve you.
These personal status matters are mentioned in the Shari'ah; there is no need for a law and its followers. The Shari'ah has not fallen short in anything. The Shari'ah is complete and has not fallen short in anything. Therefore, it is not permissible to establish personal or legal status based on laws taken from [non-Islamic] laws.

The questioner:
You mean?

The Shaykh:
Allah the Exalted knows best, and may Allah send prayers and peace upon our Prophet Muhammad, his family, and his Companions.