Is performing Wudu before Ghusl obligatory?
Chapter on Ghusl from Janabah (Major Impurity)
Al-Mughni
Book of Purification
Primary text
Performing Wudu before Ghusl is not obligatory. Scholars agree that Allah only mandated Ghusl for the majorly impure person, as indicated by Quran 5:6, "And if you are in a state of major ritual impurity, then purify yourselves." This is considered an established consensus (Ijma').
Supporting text
However, scholars agree that performing Wudu before Ghusl is recommended (Mustahabb) to emulate the Prophet (PBUH) and because it assists in and refines the Ghusl.