What is the ruling of Islamic law on choosing the 27th night of Ramadan or any other night to perform a full recitation of the Quran (khatmah) for the soul of the deceased, and what is recommended and what is disliked to avoid innovations (bid'ah)?

It is permissible to read the Quran and dedicate its reward to the deceased. However, singling out the twenty-seventh night for worship, believing it to be superior without sound evidence, falls under "innovations in addition" (bid'ah idafiyyah). This is based on the Prophet's (peace be upon him) saying: "Whoever introduces into this matter of ours that which is not from it, it will be rejected." Nevertheless, observing Laylat al-Qadr with acts of worship is a great good, and there are texts that support it.