Bidaa'h of gathering after fourty days to pray for the deceased

In the indo Pak bangladesh subcontinent, there is something in the culture where if any Muslim dies then after 40 days we observe a day of supplication and rememberance of that person. My father recently died ( XXXX) so I would like to know the islamic ruling on these kind of observences?

Praise be to Allaah.

What happens in some Muslim countries – where the friends and relatives of the deceased gather after 40 days to read Qur’aan, make du’aa’ for him and remember him – is undoubtedly bid’ah (reprehensible innovation) for which no authority has been revealed by Allaah. It is not permissible to take part in or attend such gatherings. We have to speak out against such practices. The Muslim should pray for his brother at all times, not only for three days after his death, or forty days or one year later, etc. It should be known that this is a custom of the Kuffaar and it is not permissible for us to imitate them. May Allaah help us to follow the Sunnah, and may He bless our Prophet Muhammad.