Chatam Sofer: The Rambam says that the reason Rebbe Elazar ben Azarya appeared old even though he was only 18 is because he was so involved in learning that he aged prematurely (Torah weakens a person). However, the Gemara says that he appeared old after miraculously aging overnight!
The Rambam rules that mitzvot that won’t apply when Moshiach comes are not counted among the 613 commandments. Therefore, zechirat yetziat mitzrayim is not counted (like ben Zoma).
Shiur provided courtesy of Torah Anytime