Are the supplications mentioned for the the first, fifteenth, and thirtieth days of Ramadan authentic, and to whom are these supplications attributed?

We have previously explained that there are no specific supplications for Ramadan; rather, it is a great season for worship in which it is desirable to make abundant supplications with the ma'thur (transmitted) prayers and whatever is easy. Regarding the aforementioned supplication, we have not found any marfu' (attributable) origin for it traced back to the Prophet, peace and blessings be upon him. The mentioned phrases do not generally prevent one from supplicating with them, except for the phrase "and grant me my sin in it," which is unclear in its meaning, so it is preferable to avoid it. Furthermore, restricting a supplication to a specific number or particular days and believing it to be a sunnah (prophetic tradition) is considered an innovation (bid'ah). We also draw attention to the fact that what has been authentically transmitted from the Prophet, peace and blessings be upon him, and the righteous predecessors suffices over anything else.