In 648, the Book of Jin, the official history of Jin dynasty, with Fang as its lead editor, was completed. Also in 648, when Emperor Taizong was at another summer palace, Yuhua Palace (玉華宮, in modern Tongchuan, Shaanxi), he again left Fang in charge of Chang'an, when Fang grew ill. Emperor Taizong summoned him to Yuhua Palace and had the imperial servants attend to him.
In 648, the Book of Jin, the official history of the Jin dynasty, under Fang's direction as chief editor, was finished. Additionally, in 648, when Emperor Taizong was at another summer residence, Yuhua Palace (now modern Tongchuan, Shaanxi), he again entrusted Fang with control of Chang'an, but left him in charge due to illness. Upon learning of Fang's condition, Emperor Taizong summoned him to Yuhua Palace and ordered the imperial staff to provide care.