Supplication at the completion of the Qur'an, especially in tarawih; does it have a basis?

The questioner : O Shaykh, the supplication at the completion of the Qur'an, especially in tarawih; does it have a basis?

The Shaykh : No, it has no basis. When a Muslim completes the Qur'an, it is recommended (mustahabb) for him to make supplication and gather his family. However, completing the Qur'an in this manner during the prayer of standing (qiyam al-layl), with this long supplication... this has absolutely no basis.