How can the word of Muslims be united for good and discord and division be rejected, in light of the spread of division, fragmentation, and disagreement within the Islamic Ummah?

The path to uniting the Muslims and abandoning discord is to adhere firmly to the Book of Allah and the Sunnah (definition) of His Messenger, to be steadfast upon them, to enjoin one another to them, to cooperate in righteousness and piety, and to refer everything they dispute about back to them. As Allah the Almighty says: (O you who have believed, obey Allah and obey the Messenger and those in authority among you. And if you disagree over anything, refer it to Allah and the Messenger, if you should believe in Allah and the Last Day. That is the best [way] and best in outcome) and His saying: (And in whatsoever you disagree, the decision thereof is with Allah). Referring to Allah means referring to the Qur'an, and referring to the Messenger means referring to his Sunnah. It is obligatory upon Muslims, governments and peoples, scholars and rulers, to rule by the Book of Allah and the Sunnah of His Messenger in what occurs between them, in accordance with the aforementioned verses and His saying: (But no, by your Lord, they will not believe until they make you, [O Muhammad], judge concerning that over which they dispute among themselves and then find within themselves no discomfort from what you have judged and submit in [full] submission), and His saying: (By time, Indeed, mankind is in loss, Except for those who have believed and done righteous deeds and advised each other to truth and advised each other to patience), and His saying: (And hold firmly to the rope of Allah all together and do not become divided).