Musnad Ahmad

It is narrated from Sayyiduna Ibn Amr (may Allah be pleased with him) that a man came and said, "O Messenger of Allah! I thought that shaving the head comes before the sacrifice, so I had my head shaved before offering the sacrifice." The Prophet (peace and blessings of Allah be upon him) said, "Go and offer the sacrifice, there is no harm." Another man came and said, "O Messenger of Allah! I thought that the sacrifice comes before the stoning, so I offered the sacrifice before stoning." The Prophet (peace and blessings of Allah be upon him) said, "Now go and perform the stoning, there is no harm." On that day, for every question of this nature that was asked to the Prophet (peace and blessings of Allah be upon him), he replied, "Now do it, there is no harm."