But no, by your Lord, they will not [truly] believe until they make you, [O Muhammad ﷺ], judge concerning that over which they dispute among themselves and then find within themselves no discomfort from what you (ﷺ) have judged and submit in [full, willing] submission.

Narrated 'Abdullah bin 'Amr:
Messenger of Allah (ﷺ) said:
"What befell the children of Isra'il will befall my Ummah, step by step, such that if there was one who had intercourse with his mother in the open, then there would be someone from my Ummah who would do that.
Indeed the children of Isra'il split into seventy-two sects, and my Ummah will split into seventy-three sects. All of them are in the Fire Except one sect."
He said: "And which is it O Messenger of Allah (ﷺ)?"
He (ﷺ) said: "What I am upon and my Companions."

PROPHET MUHAMMAD (ﷺ) said:
1) Indeed, whomever among you lives, he will see much differences.
2) Beware of the newly invented matters, for indeed they are astray.
3) Whoever among you sees that, then he must stick to my Sunnah and the Sunnah of the rightly guided Khulafa (Sahaaba),' cling to it with the molars.

PROPHET MUHAMMAD (ﷺ) said:
1) Whomsoever Allah guides, none can lead him astray,
2) And whomsoever Allah sends astray, none can guide.
3) The truest of word is the Book of Allah
4) And best of guidance is the guidance of Muhammad (ﷺ).
5) The worst of things are those that are newly invented;
6) Every newly-invented thing is an innovation
7) And every innovation is going astray,
8) And every going astray is in the Fire.

PROPHET MUHAMMAD (ﷺ) said:
If somebody innovates something which is not present in our religion, that thing is rejected.

PROPHET MUHAMMAD (ﷺ) said:
Whoever does something that is not in accordance with this matter of ours will have it rejected.

PROPHET MUHAMMAD (ﷺ) said:
I am your predecessor at Al-Hauh (Al- Kauthar), and some of you will be brought in front of me till I will see them and then they will be taken away from me and I will say, 'O Lord, my companions!' It will be said, 'You (ﷺ) do not know what they innovated (new things) in the religion after you left.

Narrated: Abdullah Bin Masud
PROPHET MUHAMMAD (ﷺ) said:
Among those in charge of you, after I am gone,
1) Will be men who extinguish the Sunnah and follow innovation.
2) They will delay the prayer from its proper time.”
I said: “O Messenger of Allah (ﷺ), if I live to see them, what should I do?”
He (ﷺ) said: “You ask me, O Ibn ‘Abdullah, what you should do? There is no obedience to one who disobeys Allah.”