Narrated `Abdullah bin `Amr
Allah's Messenger (ﷺ) stopped (for a while near the Jimar at Mina) during his last Hajj and the people started asking him questions. A man said, "Ignorantly I got my head shaved before slaughtering." The Prophet replied, "Slaughter (now) and there is no harm in it." Another man said, "Unknowingly I slaughtered the Hadi before doing the Rami." The Prophet (ﷺ) said, "Do Rami now and there is no harm in it." So, on that day, when the Prophet (ﷺ) was asked about anything (about the ceremonies of Hajj) done before or after (its stated time) his reply was, "Do it (now) and there is no harm."
Narrated `Abdullah bin `Amr bin Al-`As
I witnessed the Prophet (ﷺ) when he was delivering the sermon on the Day of Nahr. A man stood up and said, "I thought that such and such was to be done before such and such. I got my hair shaved before slaughtering." (Another said), "I slaughtered the Hadi before doing the Rami." So, the people asked about many similar things. The Prophet (ﷺ) said, "Do it (now) and there is no harm in all these cases." Whenever the Prophet (ﷺ) was asked about anything on that day, he replied, "Do it (now) and there is no harm in it."
Narrated `Abdullah bin `Amr bin Al-`As
Allah's Messenger (ﷺ) stopped while on his she-camel (the sub-narrator then narrated the Hadith as above, i.e. 793).