8. A number of our people have narrated from Ahmad ibn Muhammad from abu Muhammad al-Mada'iniy from Ali ibn Habib, Bayya’ al-Harawiy, who has said that ‘Isa ibn Zayd narrated from Abu ‘Abdillah عليه السلام who has said, “Amir al-Mu’minin عليه السلام has said, ‘A child teethes at the seventh year; he must be instructed to perform Salat (prayer) at the ninth; their bed must be separated at the tenth; experiences wet-dream at the fourteenth; his growth stops at twenty-one and growth of his reasoning ability stops at twenty-eight except experience.’”