Musnad Ahmad 790:133

Muhammad ibn Kathir, the brother of Sulayman ibn Kathir, narrated to us, Ja'far ibn Sulayman narrated to us, from 'Awf, from Abu Raja' al-'Utaridi, from 'Imran, that a man came to the Prophet, may Allah bless him and grant him peace, and said: "Peace be upon you (As-salamu 'alaykum)." He returned the greeting to him, then he sat down, and he (the Prophet) said: "Ten." Then another came and said: "Peace be upon you and the mercy of Allah (As-salamu 'alaykum wa rahmatullah)." He returned the greeting to him, then he sat down, and he said: "Twenty." Then another came and said: "Peace be upon you, the mercy of Allah, and His blessings (As-salamu 'alaykum wa rahmatullahi wa barakatuh)." He returned the greeting to him, then he sat down, and he said: "Thirty."