اللَّهُمَّ إِنِّي أَسْأَلُكَ الْجَنَّةَ وَأَعُوذُ بِكَ مِنَ النَّارِ
Allahumma inni as'alukal-Jannah wa a'udhu bika minan-Nar
O Allah, I ask You for Paradise and seek refuge from the Fire.
The simplest and most direct akhirah du'a. Two requests that distill all of Islamic eschatology into one sentence: get me into Jannah, keep me out of the Fire. The Prophet ﷺ said that whoever asks for Paradise three times, Paradise says: "O Allah, enter him into Paradise." And whoever seeks refuge from the Fire three times, the Fire says: "O Allah, protect him from me." Say it. Three times. Now.
Related Du'as
اللَّهُمَّ اجْعَلْ خَيْرَ عُمُرِي آخِرَهُ وَخَيْرَ عَمَلِي خَوَاتِمَهُ وَخَيْرَ أَيَّامِي يَوْمَ أَلْقَاكَ
O Allah, make the best of my life its last part, the best of my deeds their conclusions, and the best of my days the day I meet You.
Hasanاللَّهُمَّ اغْفِرْ لَهُ وَارْحَمْهُ وَأَدْخِلْهُ الْجَنَّةَ وَأَعِذْهُ مِنْ عَذَابِ الْقَبْرِ
O Allah, forgive him, have mercy on him, admit him to Paradise, and protect him from the punishment of the grave.
Sahihاللَّهُمَّ إِنِّي أَسْأَلُكَ حُسْنَ الْخَاتِمَةِ وَأَعُوذُ بِكَ مِنْ سُوءِ الْخَاتِمَةِ، اللَّهُمَّ اجْعَلْ خَيْرَ أَعْمَالِنَا خَوَاتِمَهَا وَخَيْرَ أَيَّامِنَا يَوْمَ نَلْقَاكَ
O Allah, I ask You for a good ending and I seek refuge in You from a bad ending. O Allah, make the best of our deeds their conclusions and the best of our days the day we meet You.
Hasanاللَّهُمَّ اجْعَلْ قَبْرِي رَوْضَةً مِنْ رِيَاضِ الْجَنَّةِ وَلَا تَجْعَلْهُ حُفْرَةً مِنْ حُفَرِ النَّارِ
O Allah, make my grave a garden from the gardens of Paradise, and do not make it a pit from the pits of the Fire.
Hasan