Imran bin Husain (May Allah be pleased with them) reported:
A man came to the Prophet (sallallaahu ’alayhi wa sallam) and said: “As-Salamu `Alaikum (may you be safe from evil). Messenger of Allah (sallallaahu ’alayhi wa sallam) responded to his greeting and the man sat down. The Prophet (sallallaahu ’alayhi wa sallam) said, “Ten (meaning the man had earned the merit of ten good acts).”
Another one came and said: “As-Salamu `Alaikum wa Rahmatullah (may you be safe from evil, and Mercy of Allah be upon you).” Messenger of Allah (sallallaahu ’alayhi wa sallam) responded to his greeting and the man sat down. Messenger of Allah (sallallaahu ’alayhi wa sallam) said, “Twenty.”
A third one came and said: “As-Salamu `Alaikum wa Rahmatullahi wa Barakatuhu (may you be safe from evil, and the Mercy of Allah and His Blessings be upon you).” Messenger of Allah (sallallaahu ’alayhi wa sallam) responded to his greeting and the man sat down. Messenger of Allah (sallallaahu ’alayhi wa sallam) said, “Thirty.”
[Abu Dawud and At-Tirmidhi].
Great Rewards 