الاربعين النوويه

"5"

mother of the faithful, 'Aisha (may Allah be pleased with her), who said: The Messenger of Allah (peace be upon him) said:

He who innovates something in this matter of ours [Islam] that is not of it will have it rejected [by Allah].
[Bukhari & Muslim]

In one version by Muslim it reads:

He who does an act which we have not commanded, will have it rejected [by Allah].