Compiled by Imam Yahya ibn Sharaf al-Nawawi
عن البراء بن عازب رضي الله عنهما قال: أمرنا رسول الله صلى الله عليه وسلم بعيادة المريض، واتباع الجنازة، وتشميت العاطس، وإبرار المقسم، ونصر المظلوم، وإجابة الداعى، وإفشاء السلام” ((متفق عليه))
Messenger of Allah (ﷺ) has ordered us to visit the sick, to follow the funeral (of a dead believer), respond to the sneezer (i.e., by saying to him: Yarhamuk-Allah after he says: Al-hamdu lillah), to help those who vow to fulfill it, to help the oppressed, to accept the invitation extended by the inviter; and to promote greetings (i.e., saying As-Salamu `Alaikum). [Al-Bukhari and Muslim].