Narrated Al-Bara:
The first of the companions of the Prophet (ﷺ) who came to us (in Medina), were Mus`ab bin `Umar and Ibn Um Maktum, and they started teaching us the Qur'an. Then came `Ammar, Bilal and Sa`d. Afterwards `Umar bin Al-Kkattab came along with a batch of twenty (men): and after that the Prophet (ﷺ) came. I never saw the people of Medina so pleased with anything as they were with his arrival, so that even the little boys and girls were saying, "This is Allah's Messenger (ﷺ) who has come." He (the Prophet (ﷺ) ) did not come (to Medina) till I had learnt Surat Al-Ala and also other similar Suras.
USC-MSA web (English) reference: Vol. 6, Book 60, Hadith 465
Arabic reference: Book 65, Hadith 4941