Answered by Shaykh Faraz Rabbani
Question: Is it permissible to complete a reading of the Qur’an forty days after someone’s death?
Answer: In the name of Allah, Most Merciful.
It is permitted to gather for the recitation of the Qur’an. In fact, this is a praiseworthy sunna of the Messenger of Allah (peace and blessings be upon him).
However, there is no specific proof for holding a gathering to complete the Qur’an on a specific day–and deeming that such specification is religiously binding or necessary would be a reprehensible innovation.
Thus, the ulema mention that it is best to hold such gatherings, with proper observation of Islamic propriety, on other than the 40th day after someone’s death.
And Allah alone gives success.