وَاعْتَصِمُوا بِحَبْلِ اللَّهِ جَمِيعًا وَلَا تَفَرَّقُوا
"And hold firmly to the rope of Allah all together and do not become divided."

سورۃ الانعام (6:159)
"Indeed, those who have divided their religion and become sects — you (O Muhammad) are not associated with them in anythi"
سورۃ الروم (30:31–32)
"And do not be among the polytheists,
from those who divided their religion and became sects."
(HADEES)
"A Muslim is the brother of another Muslim; he does not oppress him nor abandon him."
"The example of the believers in their affection, mercy, and compassion is that of a single"