Narrated Aisha (RA), she said, 'The Prophet (ﷺ) was leaning towards me. Then I heard him say -
اَللَّهُمَّ اغْفِرْ لِي، وَارْحَمْنِي، وَأَلْحِقْنِي بِالرَّفِيقِ الْأَعْلَى
Transliteration
Allahum-maghfir lee warhamnee wa 'alhiqnee bir-rafeeqil-'a'laa
Translation
O Allah, forgive me and have mercy upon me and join me with the highest companions (in Paradise).
Say Astaghfirullah. It means asking Allah to forgive your sins. The Prophet said it many times every day. Muslims love this for seeking forgiveness.
Say Astaghfirullah al-'Azeem alladhi la ilaha illa Huwal Hayyul Qayyum wa atubu ilayh. It asks for pardon and hope for paradise. You seek Allah's forgiveness and return to Him.
When you feel sad, say O Allah, I hope for Your mercy. Do not leave me alone even for a moment. Fix all my problems. Only You deserve worship.
Say Allahumma inni as'aluka al-jannah wa a'oodhu bika min an-nar. This means O Allah, I ask for Paradise and protection from the Fire.
Admit your mistakes. Ask for mercy with a humble heart. Say Allahumma anta rabbi la ilaha illa anta. Confess your errors. Believe that only Allah forgives.