Now, we know that the way there are 2 means to convey Durood, in the same way there are 2 means to convey our greetings (Salaam). One is Jibreel (May peace be upon him) and the other are the aforementioned angels.
There are many Hadith, both rigorously authenticated and weakly authenticated in this regard. A few Hadith are being related here.
Even though some Hadith experts have raised objections on these Hadith, but here we follow those Hadith experts who have considered them as reliable.
Qustullani (May Allah shower His Mercy on him) has related a Hadith in Masaalik ul Hunafa:
Translation: The Holy Prophet (Sallallahu alaihi wa sallam) said: The person who recites Durood once on Me out of respect to Me, then Allah Most High creates an angel from those words.
One wing of that angel is in the east and the other in the west and its feet are beneath the earth and its neck is below the ‘Arsh.
Allah Most High orders that angel: You recite Durood on that slave of Mine who has recited Durood on My Prophet (Sallallahu alaihi wa sallam).
Then that angel keeps reciting Durood till the Day of Judgment.
This has been related by Ibn Shaheen in Targheeb and by Dailami in Firdaus…
[Excerpted from Anwaare Ahmadi]