Praise be to Allah.
This should not be done, and we should warn against that, because that exposes the Qur’aanic verses to inappropriate treatment, and because some people may think that this will benefit the deceased, which is a serious mistake for which there is no basis in sharee’ah.
Similarly if the words “Laa ilaaha ill-Allaah” are written on it, this is also not prescribed in sharee’ah. Rather what is prescribed is to prompt the dying person to say these words when death is approaching, because the Prophet (peace and blessings of Allaah be upon him) said: “Prompt your dying ones to say Laa ilaaha ill-Allaah.” Narrated by Muslim.
This is so that the last words the dying person says will be Laa ilaaha ill-Allaah.
But as for writing it on his shroud or grave, that is not permitted.