Is repentance possible for one who lied about the Messenger of Allah, may Allah bless him and grant him peace, and swore a false oath (yameen ghamus)?

Lying about the Prophet (peace be upon him) is one of the greatest major sins. Some have even considered it an act of disbelief, based on his (peace be upon him) saying: "Whoever intentionally lies about me, let him prepare his seat in the Hellfire." The false oath (yamin ghamus) is one of the major sins that plunges its maker into sin or Hellfire. Whoever commits it must perform sincere repentance (tawba nasuh). The majority of scholars hold that there is no expiation for it, while the Shafi'is believe that an expiation for an oath is obligatory along with repentance. Sincere repentance erases sins, for Allah is forgiving to whoever repents, believes, and performs righteous deeds. He forgives all sins, no matter how great. Therefore, the sinner must seek forgiveness and not persist in disobedience, as stated in the divine (qudsi) and prophetic hadiths that illustrate the vastness of Allah's mercy and forgiveness.