Sunan Ibn Majah 110
سنن ابن ماجه#110Da'ifIt was narrated from Abu Hurairah that:The Prophet met 'Uthman at the door of the mosque and said: "O 'Uthman! Jibril has told me that Allah married you to Umm Kulthum for a dowry like that of Ruqayyah, provided that you treat her as you treated Ruqayyah
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniDaif
Muhammad Fouad Abd al-BaqiDaif
Shuaib Al ArnautVery Daif
Zubair Ali ZaiDaif