What are the words and phrases I should say when repenting sincerely?

It is sufficient for the penitent to say with sincerity: "My Lord, forgive me, have mercy on me, and accept my repentance, for indeed You are the Oft-Forgiving, the Most Merciful," or "O Allah, I seek Your forgiveness and repent to You from every sin." There are no specific phrases required for repentance. And whoever repents with a repentance that fulfills its conditions, Allah will accept his repentance, and one who repents from sin is like one who has no sin.