Long lifespan of the Imam عليه السلام
Kitāb al-Ghayba|Volume 1|Book 1|Chapter 49
399- وروي في خبر آخر: أن في صاحب الزمان عليه السلام شبها من يونس؛رجوعه من غيبته بشرخ الشباب.
H 399 - It is mentioned in another report that: There is a similarity between Prophet Yunus عليه السلام and Imam Mahdi عليه السلام; and it is that he would return from his occultation as a young man.