The Prophet (ﷺ) used to say:

اَللَّهُمَّ إِنِّي أَسْأَلُكَ الْجَنَّةَ وَأَعُوْذُ بِكَ مِنَ النَّارِ

Allaahumma 'innee 'as'alukal-jannata wa 'A'oodhu bika minan-naar

O Allah, I ask You for Paradise and seek Your protection from the Fire.

Reference: Sahih. Abu Dawud: 792