Abu Dawud Book 36, Hadith Number 5176.

Narated By Imran ibn Husayn : A man came to the Prophet (PBUH) and said: Peace be upon you! He responded to his salutation. He then sat down. The Prophet (PBUH) said: Ten. Another man came and said: Peace and Allah’s mercy be upon you! He responded to his salutation when he sat down. He said: Twenty. Another man came and said: Peace and Allah’s mercy and blessings be upon you! He responded to him and said when he sat down: and blessings be upon you! He responded to him and said when he sat down: Thirty.