Many people, myself included, have written about unity and given reminders about the importance of being united. Today inshaAllah I'd like to spare you my words and share some of the beauty that was displayed by the companions (may Allah be pleased with them all) regarding this topic.
During the leadership of Uthman ibn Affan (may Allah be pleased with him) he led the people in prayer during the Hajj in 29 H. At Mina he prayed four rak'ah. However, AbdulRahman ibn Awf (may Allah be pleased with him) prayed two rak'ahs. Afterwards, he went to Uthman and challenged him:
"Didn't you pray two rak'ahs in this place with the Messenger of Allah?" He said: "Yes." Then he asked: "Didn't you pray two rak'ahs with Abu Bakr?" Then he said: "Yes." He further asked: "Didn't you pray two rak'ahs with Umar?" He said: "Yes." And, he asked: "Did you not pray two rak'ahs at the beginning of your Caliphate?" He said: "Yes." And, Uthman responded to explain why in this year, in this case and in that specific situation why he prayed four rak'ahs.However, after having had that discourse, these two great and noble companions (may Allah be pleased with them) held different positions. In order to seek a third opinion, ibn Mas'ud (may Allah be pleased with him) was asked to give a ruling on this situation. ibn Mas'ud heard the situation and asked:
"Have you come to some agreement?" They said: "No." In response to that, ibn Mas'ud said: "Differing is evil. I heard he [Uthman] prayed four rak'ahs and so I led my companions in praying four."ibn Mas'ud (may Allah be pleased with him) avoided focusing on the differences and wanted not to divide the people, so not only did he follow Uthman in praying four rak'ahs, he ruled that differing is evil - not that four or two was preferable.
As we read history, let us not get side-tracked and wonder should it have been four or two (and for those who are curious, there is a difference of opinion among the Companions on the ruling of shortening prayers when travelling). What is important here is unity. ibn Mas'ud is also reported to have said: "I hate differences." Let this be a lesson for us today, as we often focus all of our attention on these differences. It is better for us to avoid controversial topics. It is not productive for us to spend large amounts of our life and time arguing about minor issues in jurisprudence.
"Indeed, those who have divided their religion and become sects - you, [O Muhammad], are not [associated] with them in anything. Their affair is only [left] to Allah ; then He will inform them about what they used to do." (6:159)Allah and His Messenger (peace and blessings be upon him) enjoined Muslims to be united and in harmony with each other - and discouraged or forbade everything that would run counter to that. Furthermore, unity is one of the aims of the Shari'ah and it is sought after by the Muslims in implementing it.
And Allah knows best.