Is repentance from backbiting valid by fulfilling the three conditions of repentance and seeking forgiveness for the one who was backbited without asking for their pardon or praising them in gatherings, citing the statements of Hudhayfah and Abdullah ibn al-Mubarak: "The expiation for one whom you have backbited is that you seek forgiveness for them"?

Your repentance is, Allah Almighty willing, valid, even if you did not ask him for forgiveness. However, you should praise him in the situations where you slandered him, and supplicate and seek forgiveness for him, and dedicate a good deed to him that stands in place of your slander. The correct view is that there is no need to inform him; rather, it is sufficient to seek forgiveness and mention his good qualities in the situations where you slandered him.