How do we know that an act is a religious innovation?

Question:
In the following paragraph, Shaykh 'Abd al-'Aziz says: How do we know that this act is a religious innovation?

Answer:
It is known to be a religious innovation if it is not prescribed. If there is no evidence that it is prescribed, then worshipping Allah with it is a religious innovation. Any act that you do not know is prescribed from the Qur'an or the Sunnah, worshipping Allah with it is a religious innovation.
For example, the worship of the Mawlid, which takes place in Rabi' al-Awwal, the birthday of the Prophet (peace and blessings be upon him). Gathering and celebrating this Mawlid is an example. Also, the prayer of al-Ragha'ib, which is on the first Friday of Rajab, where one prays a specific prayer; this is a religious innovation. Celebrating the night of the Isra' and Mi'raj is also an invented act of worship, a religious innovation.
For example, if a person calls people to a prayer in the Duha time, making it a prayer that he calls people to perform in congregation as a custom, saying: "This is a sixth prayer." This is a religious innovation... and so on. That is, he invents a worship that Allah has not prescribed, and this is called a religious innovation.
Or he might say, for example: "It is prescribed for people to gather to fast a specific month every year." It becomes a second month where they all fast Rajab, or they fast Rabi' al-Awwal, meaning: Ramadan is not enough. He tells people: "Ramadan is not enough for you; rather, you should fast a second month." This is from the religious innovations. Yes.

The presenter: May Allah reward you with good.