It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him), he said: The greatest miser is the one who is miserly in greeting (salam), and the one who suffers loss is the one who does not reply to the greeting. If a tree comes between you and your brother, and you are able to initiate the greeting, then do so.
Hadith Referenceالادب المفرد / كتاب السلام / 1015
Hadith Gradingالألبانی:ضعيف الإسناد موقوفًا
Hadith Takhrij«ضعيف الإسناد موقوفًا : تفرد المصف بهذا التفصيل»
Explanation & Benefits
Shaykh Maulana Usman Muneeb
Benefits and Issues: The mentioned narration is weak due to the narrator of this chain, Kinanah. However, its first sentence is authentic as a marfu‘ (attributed to the Prophet sallallahu alayhi wa sallam), and the last sentence is authentic both as marfu‘ and mawquf (attributed to a Companion). (Al-Sahihah of Al-Albani, no. 518)
Source: Fadlullah al-Ahad: Urdu Commentary on al-Adab al-Mufrad, Page: 1015