رَبَّنَا آتِنَا فِي الدُّنْيَا حَسَنَةً وَفِي الْآخِرَةِ حَسَنَةً وَقِنَا عَذَابَ النَّارِ
Rabbana atina fid-dunya hasanatan wa fil-akhirati hasanatan wa qina 'adhaaban-nar
Notre Seigneur, donne-nous du bien dans ce monde et du bien dans l'Au-delà, et protège-nous du châtiment du Feu.
Comprehensive dua that can be said before salam or anytime
This was the most frequent dua of the Prophet (PBUH), asking for good in both worlds.