What is the ruling for someone who had intercourse with his wife at night and slept in a state of ritual impurity (junub) until he woke up on a Ramadan day around 10:00 AM, and what should he do?

A man must perform ghusl for janabah, pray the missed Fajr prayer, and complete his fast. The proof for this is what was narrated by Aisha and Umm Salamah, that the Messenger of Allah, peace and blessings be upon him, would be overtaken by dawn while he was in a state of janabah from his family, then he would perform ghusl and fast.