What is the difference between a permissible experience for supplication (du'a) and innovation (bid'ah), and how is the speech of the Salaf understood in that regard?

A number of scholars are of the opinion that it is permissible to rely on experience in matters of healing. And whoever recites certain verses or supplications, free from polytheism, for a specific purpose, following the experiences of the righteous without attributing them to the Sharia (definition), it is hoped that there will be no sin upon him. Nevertheless, what is more appropriate is to adhere to what has been transmitted and narrated. It must be believed that the entire Qur’an is a healing. As for the reciter’s claim of specific properties for a ruqyah (definition) without legal evidence, it is considered an innovation. Ibn Taymiyyah mentioned the narration of Ibn Abbas which indicates the permissibility of specifying certain verses in ruqyah, such as writing specific verses for difficult childbirth, and this has been tried and tested.