When anyone of you meets his brother, let him greet him with peace. If a tree, a wall, or a rock comes between them and then he meets him, let him greet him with peace again.
Chapter: Regarding when a man parts from another, then meets him again, he should greet him with the salam
Authentic4 scholars’ gradesCompanion’s words (mawquf)Sunan Abu Dawud 5200
Abu Hurayrah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said:
"When any of you meets his brother, let him greet him with peace. If a tree, a wall, or a rock comes between them and then he meets him, let him greet him with peace again."
The Prophet (may Allah's peace and blessings be upon him) urges the Muslim to greet his fellow Muslim with peace whenever he meets him; even if they are walking together and something separates between them, like a tree, a wall, or a big rock, and then he meets him, he should greet him with peace once again.
Lessons
It is recommended to spread the greeting of peace and repeat it whenever there is a change in state.
The Prophet (may Allah's peace and blessings be upon him) was extremely keen on spreading the Sunnah of exchanging the greeting of peace excessively, given the affection and familiarity that it fosters among Muslims.
The greeting of peace is to say: "As-salāmu ‘alaykum" (peace be upon you) or "As-salāmu ‘alaykum wa rahmatullāhi wa barakātuh" (may Allah's peace, mercy, and blessings be upon you), apart from the handshaking that takes place upon meeting for the first time.
The greeting of peace is a form of supplication, and Muslims do need to supplicate for each other even if this is done repeatedly.
Explanation in Arabic
يَحُثُّ النبيُّ صلى الله عليه وسلم المُسلمَ بالسلام على أخيه المسلمِ كلّما لَقِيَه، حتى وإنْ كانا يَسيران معًا وفَصَلَ بينهما فاصلٌ كشجرة أو جِدار أو حَجَر كبير، ثم لقيه بعدُ فلْيسلِّم عليه مرة أخرى.
استحباب إفْشاء السلام، وأنْ يُكَرَّر عند كل تَغَيُّر حال.
شدَّة حرصِه صلى الله عليه وسلم على إفشاء سنة السلام والمبالغة فيه؛ لما فيه من جَلْبِ المودّة والأُلفة بين المسلمين.
السلام هو قول: (السلام عليكم) أو (السلام عليكم ورحمة الله وبركاته)، غير المصافحة التي تَحدُث عند التلاقي أول مرة.
السلام دعاء، والمسلمون بحاجة إلى أن يدعو بعضهم لبعض ولو تَكرَّر ذلك.