https://www.duas.org/mobile/ramadan-dua-last-day-night.html Imam Ja`far al-Sadiq (a.s) was noted as saying: As for anyone who bids farewell to the month of Ramadan with the following supplication, Almighty Allah will forgive him before morning and will confer upon him with the bliss of submission before Him (i.e. Almighty Allah): اللّهُمّ لا تَجْعَلْهُ آخِرَ العَهْدِ من صِيَامِي لِشَهْرِ رَمَضَانَ، allahumma la taj`alhu akhira al`ahdi mn siyamy lishahri ramazana O Allah: (please) do not decide my observance of fasting in this month of Ramazan to be the last of my(life's) observance of fasting. وَأَعُوذُ بِكَ أَنْ يَطْلُعَ فَجْرُ هذِهِ اللّيْلَةِ إِلاَّ وَقَدْ غَفَرْتَ لِي wa a`udhu bika an yatlu`a fajru hadhihi allaylati illa wa qad ghafarta le I take refuge with Thee lest the dawn of this night breaks forth without me having been positively forgiven.