All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There are several definitions, roughly similar in meaning, for permissible acts. Ibn Qudaamah from the Hanbali School, said that it refers to anything that Allah permits a person to do and failing to do it does not incur praising or dispraising the person.
As regards Bid‘ah, Ash-Shaatibi from the Maaliki School, defined it as an innovated religious act which falsely appears to be in accordance with religion. It is an exaggerated way of worshipping Allah.
Therefore, it is an obligation to refrain from a Bid’ah and it is forbidden to do it as it is an innovation and Allah did not permit it.
Any Muslim who performs acts of Bid‘ah will be punished and any Muslim who refrains from performing Bid‘ah with the intention of obeying Allah will be rewarded. Moreover, if a Muslim does a permissible act with the intention of pleasing Allah, he will be rewarded.
Allah knows best.