The Prophet (ﷺ) said to 'Aa'ishah (RA): You say -

اَللَّهُمَّ إِنَّكَ عَفُوٌّ كَرِيمٌ تُحِبُّ الْعَفْوَ فَاعْفُ عَنِّي

Allaahumma innaka 'afuwwun karim, tuhibbul-'afwa, fa'fu 'anni

O Allah, You are Most Forgiving, Generous. You love forgiveness; so forgive me.

Reference: Sahih (Albani). Tirmidhi: 3513