Du'a on completing the Qur'an: O Allah, have mercy on me through the Quran

اللَّهُمَّ ارْحَمْنِي بِالْقُرْآنِ وَاجْعَلْهُ لِي إِمَامًا وَنُورًا وَهُدًى وَرَحْمَةً اللَّهُمَّ ذَكِّرْنِي مِنْهُ مَا نَسِيتُ وَعَلِّمْنِي مِنْهُ مَا جَهِلْتُ وَارْزُقْنِي تِلَاوَتَهُ آنَاءَ اللَّيْلِ وَأَطْرَافَ النَّهَارِ وَاجْعَلْهُ لِي حُجَّةً يَا رَبَّ الْعَالَمِينَ

Allahummar-hamni bil-qur'an, waj'alhu li imaman wa nuran wa hudan wa rahmah, Allahumma dhakkirni minhu ma nasitu, wa 'allimni minhu ma jahiltu, warzuqni tilawatahu ana'al-layli wa atrafan-nahar, waj'alhu li hujjatan ya rabbal-'alamin

O Allah, have mercy on me through the Quran and make it for me a guide, a light, a guidance, and a mercy. O Allah, remind me of what I have forgotten from it, teach me what I am ignorant of from it, and grant me its recitation during the hours of the night and the edges of the day, and make it a proof for me, O Lord of the worlds.

A traditional supplication recorded by al-Ghazālī in Iḥyāʾ ʿUlūm al-Dīn; not a narration from the Prophet (peace be upon him).