It is mentioned in the sacred kitab, "Dalayal-ul-Khaiyrat", that the
Holy Prophet Mohammad (sallalahu alaihi wasallam) said:
"When any individual recites Durood Shareef on me that Durood Shareef,
after getting out of his mouth goes forth immediately to all the plains
and rivers of the world: towards the East and the West, and no plain or
river in the world is left over which this Durood Shareef is not
passed-over from. The Durood Shareef proclaims,
"I have recited by such and such an individual, son of such and such
person, who recited unto Mohammad (sallalahu alaihi wasallam) supreme to all creations of all the (eighteen hundred or eighteen thousand) worlds."
So there remain no object or thing that does not recite Durood Shareef
on to the individual who recites Durood Shareef on the Holy Prophet
Mohammad (sallalahu alaihi wasallam).
And from that Durood Shareef there is brought into being a bird that
happens to have seventy thousand wings. In each wing there are seventy
thousand heads. In each there are seventy thousand feathers. In each
feather there are seventy thousand heads. In each head there are seventy thousand faces and in each face seventy thousand mouths and in each mouth seventy thousand tongues. By each tongue chirps the glorification of Allah Ta'ala in seventy thousand kinds of dialects the chirpings; and the Almighty Allah gets the compensation of all the invocations of the glorifications of Allah written down in the celestial account of the individual who happens to have initially recited the Durood Shareef onto the Holy Prophet Muhammad (sallalahu alaihi wasallam)."
Therefore, the total reward for the person reciting Durood Shareef once
On top of this reward, each time a person recites Durood Shareef Allah
Subhana Wa Ta'ala sends blessings at least ten times over.
How profusely benevolent Allah Ta'ala is in granting us His favours on
our recitations of Durood Shareef on His Beloved Prophet Muhammad (sallalahu alaihi wasallam)!