How did the Prophet Aaron (peace be upon him) err while being infallible, and why did he not forbid his people from worshipping the calf in Moses' absence, leading Moses to reproach him severely upon his return? And does revelation descend upon prophets as it does upon messengers? And did Aaron die before or after Moses (peace be upon them)?

The prophets are infallible in conveying the messages of their Lord, protected from committing major sins. Minor sins may occur from them, but they are not condoned; rather, they hasten to repent from them. Aaron forbade his people from worshipping the calf, explaining to them that it was a trial, and commanded them to follow him and obey his command. When Moses returned from his Lord, having been informed that his people had been tempted by the calf, he became angry and seized his brother by the head, dragging him towards him out of fear of his shortcomings. When Aaron's innocence became clear to him, he said: "(My Lord, forgive me and my brother and admit us into Your mercy, for You are the Most Merciful of those who show mercy)." Revelation is sent to prophets just as it is sent to messengers. Aaron died before Moses, peace be upon them, in the wilderness.