Sunan Ibn Majah, Volume 5, Book 36, Hadith 4083 (DarusSalam) ⓘ
It was narrated from Abu Sa'eed Al-Khudri that the Prophet said: "The Mahdi will be among my nation. If he lives for a short period, it will be seven, and if he lives for a long period, it will be nine, during which my nation will enjoy a time of ease such as it has never enjoyed. The land will bring forth its yield and will not hold back anything, and wealth at that time will be piled up. A man will stand up and say: 'O Mahdi, give me!' He will say: 'Take.'"
حَدَّثَنَا نَصْرُ بْنُ عَلِيٍّ الْجَهْضَمِيُّ، حَدَّثَنَا مُحَمَّدُ بْنُ مَرْوَانَ الْعُقَيْلِيُّ، حَدَّثَنَا عُمَارَةُ بْنُ أَبِي حَفْصَةَ، عَنْ زَيْدٍ الْعَمِّيِّ، عَنْ أَبِي صِدِّيقٍ النَّاجِيِّ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، أَنَّ النَّبِيَّ ـ صلى الله عليه وسلم ـ قَالَ " يَكُونُ فِي أُمَّتِي الْمَهْدِيُّ إِنْ قُصِرَ فَسَبْعٌ وَإِلاَّ فَتِسْعٌ فَتَنْعَمُ فِيهِ أُمَّتِي نَعْمَةً لَمْ يَنْعَمُوا مِثْلَهَا قَطُّ تُؤْتَى أُكُلَهَا وَلاَ تَدَّخِرُ مِنْهُمْ شَيْئًا وَالْمَالُ يَوْمَئِذٍ كُدُوسٌ فَيَقُومُ الرَّجُلُ فَيَقُولُ يَا مَهْدِيُّ أَعْطِنِي فَيَقُولُ خُذْ " .
also referenced under: Hadith 4083 (Reference) & Book 36, Hadith 158 (In-Book)