Meaning: Whatever is from the matters of worship or from matters of creed and beliefs or from sayings and it does not have a proof from the Book and the Sunnah
Explanation by Shaykh Saalih al Fawzaan
Innovation is whatever is from the matters of worship or from matters of creed and beliefs or from sayings and it does not have a proof from the Book and the Sunnah (that is an innovation). He sall Allaahu`alayhi wa sallam said, “Whoever does an action which our affair is not in accordance with, it is rejected.”
And in a narration, “Whoever introduces into this affair of ours that which is not from it then it is rejected.”
And he said, “And beware of newly introduced matters for every newly introduced matter is a bid’ah (an innovation) and every innovation is misguidance”
So innovation is whatever has been introduced into the religion and it is not from it. And how can it be known that it is not from it? If it does not have a daleel,(a proof), then it is not from the Religion, because Allaah the Majestic and Most High says:
- "This day have I completed your Religion for you"
Sooratul-Maa-idah (5): aayah 3
Taken from Ithaaf ul Qaari (Explanation of Sharhus Sunnah) of Shaykh Saalih al Fawzaan, volume 1 page 59
Translator Abu Talhah Dawood – words in brackets & footnotes are translator’s – taken from www.ittibaa.com
 Reported by Muslim in his Saheeh (1718) and reported by al-Bukhaaree in disconnected form in his Saheeh from a hadeeth of Aa`ishah radiy Allaahu `anhaa.
 Reported by al-Bukhaaree in his Saheeh (hadeeth 2550) and by Muslim in his Saheeh (hadeeth1718) from (a hadeeth of) Aa`ishah radiy Allaahu
 This is part of a hadeeth of al-`Irbaad ibn Saariyah radiyAllaahu `anhu, and itschecking has preceded. (The checking of this hadeeth is reported by Imaam Ahmad and Aboo Daawood and at-Tirmithee and Ibn Maajah and it was declared authentic by Shaykh al-Albaanee).