It is narrated from Hazrat Abu Masood (may Allah be pleased with him) that the Holy Prophet (peace and blessings be upon him) said: A Muslim has four rights over another Muslim: when he invites him, he should accept it; when he sneezes, he should respond; when he is ill, he should visit him; and when he passes away, he should attend his funeral.
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 22342
Hadith Gradingحکم دارالسلام:صحيح لغيره، حكيم بن أفلح حجازي، إن كان هو بصري أيضا، فالإسناد محتمل للتحسين