Is the recitation of a Surah from the Quran a specific number of times with the intention of reward, which some Sufis have justified as a divine inspiration to draw people closer to God, considered an innovation (bid'ah) or not, and how can one distinguish between sincerity and insincerity in such acts?

The Awliya' (devout servants) of Allah Almighty are the pious believers who do not contradict what came from the Prophet, peace be upon him, nor do they add to or subtract from the religion. The Prophet, peace be upon him, warned against innovations (bid'ah) because the religion has been perfected. Whoever wishes to distinguish a Wali of Allah from others should observe their commitment to congregational prayer, their avoidance of devouring people's wealth unjustly, and their not transgressing the Sharia (definition). It is not permissible to innovate dhikr (remembrances), awrad (liturgies), or supplications other than what has come in the authentic prophetic Sunnah (definition), for every action not commanded by the Lawgiver is rejected. Dhikr and supplications are among the best acts of worship, but their foundation is based on textual evidence (tawqif) and following, not on innovation. Prophetic dhikr are the best a Muslim can seek. It is not permissible to legislate a type of dhikr or supplications that are not legislated and make them a regular act of worship, because this is an innovation in religion.