Du'a for a mother's mercy via Qur'an

اللَّهُمَّ ارْحَمْ أُمِّي بِالْقُرْآنِ، وَاجْعَلْهُ لَهَا نُورًا وَهُدًى وَرَحْمَةً

Allahummar-ham ummi bil-Qur'an, waj'alhu laha nuran wa hudan wa rahmah

O Allah, have mercy on my mother by the Qur'an, and make it a light, guidance, and mercy for her.

A general supplication, not a narration from the Prophet (peace be upon him).