Hazrat Abdullah bin Salaam (radhiyallahu ‘anhu) says:

فلما رأيت وجهه عرفت أن وجهه ليس بوجه كذاب

The moment my gaze fell onto his blessed face, I realised that his face was not the face of a liar.

The very first words I heard from his tongue were:

أيها الناس أطعموا الطعام وأفشوا السلام وصلوا الأرحام وصلوا بالليل والناس نيام تدخلوا الجنة بسلام

O People! Feed the creation, make greeting with salaam a common practice among you, maintain family ties and perform salaah at night while people are asleep, you will enter Jannah with peace.

Hazrat Abdullah bin Salaam (radhiyallahu ‘anhu) mentions:

I was aware of Rasulullah’s (sallallahu ‘alaihi wasallam) name, attributes and physical description long before this, however I never revealed this to anyone. At the time when Rasulullah (sallallahu ‘alaihi wasallam) came to Madinah Munawwarah and I heard of his arrival, I was at the top of a date palm tree, and in extreme happiness and joy, I called out the takbeer “Allahu Akbar!”.

On seeing my joy and happiness, my paternal aunt (father’s sister), Khaalidah bint Haaris, remarked, “If you had heard of the arrival of Nabi Musa (‘alaihis salaam), perhaps you would not have been as overjoyed as you are now.” I replied, “By Allah! This person (who is claiming nubuwwah) is also the brother of Nabi Musa (‘alaihis salaam). He has been sent with the same Deen that Nabi Musa (‘alaihis salaam) was sent with.”

My aunt then asked, “O my nephew! Is this the same Nabi regarding whom we have been informed that he will be sent just before the advent of Qiyaamah?” “Yes,” I replied, “this is the very same Nabi.”

I then left home, presented myself before Rasulullah (sallallahu ‘alaihi wasallam) and embraced Islam. Thereafter, I returned home, invited my family members to embrace Islam, and they all embraced Islam as well.

(Extracted from Seeratul Mustafa 1/414-416)