Astaghfirullāh (three times)
Allāhumma antas-salām,
wa minkas-salām,
tabārakta yā dhal-Jalāli wal-'Ikrām.
I seek the forgiveness of Allah (three times).
O Allah, You are Peace and from You comes peace.
Blessed are You, O Owner of majesty and honor.
Reference:
Muslim 1/414.