Is bathing on Friday obligatory or Sunnah, and what are the proofs for that?

Scholars have differed concerning the ruling on ghusl (ritual bath) for Jumu'ah (Friday prayer). The majority of scholars hold that it is a recommended Sunnah and not obligatory, citing as evidence the hadith of the man who entered while Umar was delivering the khutbah (sermon) and had not performed ghusl, and the hadith: "Whoever performs ablution, that is good enough; but whoever performs ghusl, then ghusl is better," and the saying of the Prophet, peace be upon him: "If only you were to perform ghusl on the day of Jumu'ah." They interpret the hadiths that command it as indicating recommendation. In contrast, the Zahiris and some of the Salaf held it to be obligatory, citing as evidence the apparent meaning of the hadiths that command it, such as the hadith: "It is obligatory upon every adult (to perform ghusl)." The majority, however, believe that the meaning of "obligatory" here is "highly emphasized." The Four Schools of thought are in agreement regarding the recommendation of ghusl for Jumu'ah, and this is the preponderant opinion.