Sahl ibn Ziyad reported from Ahmad ibn Muhammad, from Ibn Abi Nasr, from one of our companions, who said:
Abu Abdillah عليه السلام said: "The age at which a woman is considered to have reached menopause (ya's min al-maheed) is fifty years."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 1, p. 421