22-23 Muhammad ibn al-Hassan - may God be pleased with him - narrated that Ahmad ibn Idris quoted Muhammad ibn Ahmad ibn Yahya, on the authority of Muhammad ibn al-Sindy, on the authority of Ali ibn al-Hikam, on the authority of Davood ibn al-Nue’man, on the authority of Sayf al-TAmmar, on the authority of Abi Basir that Aba Abdullah as-Sadiq (MGB) said,

When a servant reaches the age of thirty-three, he has reached perfect maturity. When he reaches the age of forty years, he has attained his ultimate progress. Hence as he enters forty‑one his powers are on decline, and it is befitting for one at fifty to consider himself like someone in his death throes.”