Shaikh Uthaimeen, may Allāh have mercy on him, was asked, “What is the ruling concerning the du’aa for finishing the recitation of the Qur’an in the night prayer in Ramadaan?”
He replied, “I don’t know of any Sunnah from the Prophet ﷺ or the Companions either connected to finishing the recitation of the Quraan during the qiyaam al-lail in Ramadaan. The most that has been narrated about that is that Anas ibn Maalik, may Allāh be pleased with him, would gather his family and supplicate when he would finish reciting the whole Qur’an, and that was not in the prayer.”
Fataawaa Arkaan al-Islaam, p. 354.