Mr. Adnan Oktar's explanations of hadiths related with Hazrat Mahdi (pbuh)
Ibn Hacer says;
"First of all, the Messenger of God (saas) gave glad tidings to his ummah, especially Ahl-al Bayt, in many matters. He said that they will be saved from all sorts of persecution and torture." That means Ahl-al Bayt will suffer persecution and torture. But "...they will be saved," so it will not continue. "And that can only be connected to justice which will be ensured for a long time. A short time of seven or nine years will not be enough for that." You know that the global reign of the Mahdi (pbuh) is said to be seven or nine years.
"Secondly, the system of the Mahdi will reign over the world just like Dhul'Qarnayn and Solomon. Mosques and buildings will be constructed in other countries." Meaning he will start a great architectural artistry initiative. "A short period of time like nine years will not be enough for the effort he will make and the other tasks he will perform." Meaning that showing efforts for nine years would not be enough.
"Thirdly in his time there will be an increase in the life-spans." The increase in the life-spans would mean that Mahdi will have a long life as well. Otherwise the increase in life spans will have no significant meaning. I mean the hadith would have no meaning if there is no increase in the life-span of the Mahdi.
"Fourthly he will make a peace agreement with the Greeks for nine years." Meaning he will make a peace agreement with the non-Muslims. "According to this, he will be living in Constantinople." Meaning he will be living in Rome, in Istanbul. "His going there and coming back would of course take years." Meaning Mahdi (pbuh) will stay in Rome for a long time. "He will struggle against the Sufyan. He will spiritually conquer India and other countries." And that would certainly take [several] years. All those tasks show that the reign would last more than nine years. That means the reason why it is written down as seven years is that it covers the time he will reign entirely over all countries. "The global reign of Islamic morality would last for seven years. And that would take place after he conquers the city of Rome. The restriction of nine years covers Constantinople (his spiritual conquest of Istanbul); it is limited with 19 years." Look, 19 comes up here as well, the number 19 is frequently referred to in the Qur'an. This is about him defeating the Sufyan - antichrist - and ruling over the other countries and all people pledging allegiance to him; all these matters cover those 19 years. Meaning the global reign of the Mahdi (pbuh) will not be only for nine years but 19 years, insha'Allah.