It is narrated from Mujahid (may Allah have mercy on him) that a funeral passed by Sayyiduna Ali (may Allah be pleased with him), and some people stood up (out of respect), whereupon he asked: "What is this?" The people said: Sayyiduna Abu Musa (may Allah be pleased with him) (used to do so). Then Sayyiduna Ali (may Allah be pleased with him) said: "The Messenger of Allah (peace and blessings be upon him) stood (for a funeral) only once, and after that he (peace and blessings be upon him) did not stand (out of respect)."
Hadith Referenceمسند أبي يعلى الموصلي / مسند علي بن أبي طالب رضي الله عنه / 339
Hadith Takhrij«قال سعيد بن محمد السناري: صحيح: مضى الكلام عليه [برقم/ 266]. ف» «رواه عن مجاهد به. ولم يذكر فيه "عبد الله بن سخبرة"، مسند ابویعلیٰ ترقیم الاثری: 334»