Is there any merit in supplicating after completing the recitation of the Qur’an, and is it permissible to supplicate in congregation when one of them completes the Qur’an?

It is recommended to supplicate upon completing the recitation of the Qur’an, and this was practiced by the Salaf (early Muslims). Imam Ahmad explicitly stated the desirability of gathering one's family to supplicate after completing the Qur’an, citing the actions of Anas ibn Malik and Ma'mar as evidence. It is also narrated from Mujahid that supplications are answered upon completing the Qur’an and that mercy descends, and from Ibn Mas'ud that whoever completes the Qur’an has an answered supplication.