‘Uthmaan’s compilation of the Mushaf in one style (harf)

It was proven that the Messenger of Allaah (blessings and
peace of Allaah be upon him) said: “This Qur’aan has been revealed in seven
styles, so recite whichever is easiest.” And the scholars said: they are
close in meaning but different in wording. 

When ‘Uthmaan (may Allaah be pleased with him) heard of the
differences among the people and Hudhayfah (may Allaah be pleased with him)
came to him and said “Save the people,” he consulted the Companions who were
still alive at this time, such as ‘Ali, Talhah, al-Zubayr and others, and
they suggested compiling the Qur’aan in one style, so that the people would
not differ. So he compiled it (may Allaah be pleased with him), and he
formed a four-man committee for that task, headed by Zayd ibn Thaabit (may
Allaah be pleased with him). So they compiled the Qur’aan in one style, and
copied it and distributed it to the various regions so that the people could
rely on it and so as to put an end to disputes. 

With regard to the seven recitations or ten recitations, they
are present in what was compiled by ‘Uthmaan, and have to do with adding a
letter or omitting a letter, or elongating or shortening a vowel. All of
that is included in the one style that ‘Uthmaan (may Allaah be pleased with him) compiled. The intention behind that was to preserve the word of Allaah and protect people from differences that could harm them or cause fitnah among them. Allaah has not enjoined reciting it in the seven styles, rather the Prophet (blessings and peace of Allaah be upon him) said: “Recite whichever is easiest.” So the people’s agreeing upon one style is a good action for which ‘Uthmaan and the Companions (may Allaah be pleased with them) are to be appreciated, because it made things easier for people and prevented a cause of dispute among the Muslims. End quote.