What is the sunnah way to say salam or greeting in Islam?

Question

What is the sunnah way of saying salam or greeting someone in Islam? I am searching sunnah.com but I found only greet your fellow muslim but how? i.e. Assalamu Alaikum or Salaam only

The Prophet (sallallahu 'alaihi wa sallam) said, "The young should greet the old, the passer by should greet the sitting one, and the small group of persons should greet the large group of persons. "

حَدَّثَنَا مُحَمَّدُ بْنُ مُقَاتِلٍ أَبُو الْحَسَنِ، أَخْبَرَنَا عَبْدُ اللَّهِ، أَخْبَرَنَا مَعْمَرٌ، عَنْ هَمَّامِ بْنِ مُنَبِّهٍ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ يُسَلِّمُ الصَّغِيرُ عَلَى الْكَبِيرِ، وَالْمَارُّ عَلَى الْقَاعِدِ، وَالْقَلِيلُ عَلَى الْكَثِيرِ ‏"‏‏.‏

Reference : Sahih al-Bukhari 6231

In-book reference : Book 79, Hadith 5

For e.g. I have read the above Hadith which doesn't mention any method..

Answer 1

Salam is a way of greeting when you meet another Muslim whether you know them or not. The proper way of Salam is saying Asalamu Alaikum(Peace be upon you), Asalamu Alikum Warahmatullah(Peace and mercy of Allah be upon you) or Asalamu Alikum Warahmatullah Wabarakatoh(Peace, mercy and blessing of Allah be upon you). If I were to put them on a scale of good, better and best; I would say the first one is good, the second one is better and the third one is the best.

Imams Abu-Dawood and At-Termithi reported in a good hadith that a man came to the prophet (S.A.W.) and said, "Assalamu Alikum." The prophet responded and the man sat down. The prophet said, "Ten rewards."

Another man came and said, "Assalamu Alikum Wa Rahmatullh." The prophet responded and the man sat down. The prophet said, "twenty rewards."

Then another man came and said: Assalamu Alakum Wa Rahmatulah Wa Barakatuh. The prophet responded and the man sat down. The prophet said, "thirty rewards." source

When did it start?

Imams Bukhari and Muslim reported that the prophet (S.A.W.) said, "When Allah created Adam he told him to go and say Assalamu Alikum to a group of Angels and listen to their reply. It is your greeting and the greeting of your descendants. Adam went and said: Assalamu Alikum they said Assalamu Alikum Wa Rahmatulah."source

You mentioned the etiquette, so I won't repeat it here. For more information, follow the link embedded in my answer.