Rasulullah (sallallahu ‘alaihi wasallam) then instructed Hazrat Abdullah bin Zaid (radhiyallahu ‘anhu) to teach Hazrat Bilaal (radhiyallahu ‘anhu) the words of the azaan which were taught to him in the dream so that Hazrat Bilaal (radhiyallahu ‘anhu) may call out the azaan in those words. Rasulullah said to Hazrat Abdullah bin Zaid (radhiyallahu ‘anhu), “Let Bilaal call out the azaan, as he has a louder voice than you.”

Hazrat Bilaal (radhiyallahu ‘anhu) then called out the azaan. When the words of the azaan reached the ears of Hazrat Umar (radhiyallahu ‘anhu) (and he also came to know about the dream of Hazrat Abdullah bin Zaid [radhiyallahu ‘anhu]), he immediately left his home, pulling his shawl behind (in haste), and came to Rasulullah (sallallahu ‘alaihi wasallam).

As Hazrat Umar (radhiyallahu ‘anhu) appeared before Rasulullah (sallallahu ‘alaihi wasallam), he said:

والذي بعثك بالحق لقد رأيت مثل الذي أري

“O Rasulullah (sallallahu ‘alaihi wasallam)! By the Being who has sent you with the haq (the truth of Islam), I have also seen a similar dream which he was shown (wherein the words of azaan were taught to me).”

Upon hearing this, Rasulullah (sallallahu ‘alaihi wasallam) exclaimed, “May Allah be praised (that you have also been shown the same dream)!”

(Extracted from Seeratul Mustafa 1/442-443)