Mishkat al-Masabih 27 Fitan كتاب الفتن 76

وَعَنْهُ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فِي قِصَّةِ الْمَهْدِيِّ قَالَ: ” فَيَجِيءُ إِلَيْهِ الرَّجُلُ فَيَقُولُ: يَا مَهْدِيُّ أَعْطِنِي أَعْطِنِي. قَالَ: فَيَحْثِي لَهُ فِي ثَوْبِهِ مَا اسْتَطَاعَ أَنْ يَحْمِلَهُ ” . رَوَاهُ التِّرْمِذِيّ

He reported the Prophet as saying in the course of the story about the Mahdi that a man will come to him and say, “Give me, give me, Mahdi,” and he will pour into His garment as much as he is able to carry. Tirmidhi transmitted it.