Reference : Hisn al-Muslim 51

اللّهُـمَّ اكْتُـبْ لي بِهـا عِنْـدَكَ أَجْـراً ، 
وَضَـعْ عَنِّـي بِهـا وِزْراً ، 
وَاجْعَـلها لي عِنْـدَكَ ذُخْـراً ، 
وَتَقَبَّـلها مِنِّي كَمَا تَقَبَّلْتَهَا مِنْ عَبْدِكَ دَاوُدَ.
Allāhummak’tub lī bihā `indaka ajra, 
waḍa` `annī bihā wizra,
waj`alhā lī `indaka dhukhra, 
wa taqabbal’hā minnī kamā taqabbal’tahā min `abdika Dāwūd.


O Allah, write it as a reward for me, 
and release me from a burden for it, 
and make it a treasure for me with You.
Accept it from me as You accepted it from your servant Dawud.

Reference:
At-Tirmidhi 2/473, and Al-Hakim who graded it authentic and Ath-Thahabi 
agreed 1/219.

Chapter: When prostrating due to recitation of the Quran