Abu Talha Al Ansaree (R.A) said “one morning the messenger of Allah was in a cheerful mood and looked happy. They said Oh messenger of Allah, this morning you are in a cheerful mood and look happy, He said `of course, just now, someone (an angel) came to me from my Lord and said, whoever among your Ummah sends Salams upon you, Allah will record for him/her ten good deeds and will erase for him ten evil deeds, and will raise his status by ten degrees and will return his greeting with something similar to it”

Surah Ahzaab (33:56)

The verse is as follows:
Indeed, Allah confers blessing upon the Prophet, and His angels [ask Him to do so]. O you who have believed, ask [ Allah to confer] blessing upon him and ask [ Allah to grant him] peace.