Abdullah bin Abbas reported,

They used to consider performing Amra during the months of Hajj to be one of the gravest sins on earth, and they called Muharram "Safar." They would say, "Once the camels' sores have healed and the tracks of the pilgrims have faded, Amra becomes lawful for whoever wishes to perform it."The Messenger of Allah ﷺ and his companions arrived on the morning of the fourth day, having entered the state of ihram for Hajj. The Prophet ﷺ commanded them to convert their intention into Amra.They asked, "Messenger of Allah, what kind of release from ihram is this?"He replied, "Complete release."

Bukhari 3832

Sahih

حدثنا مسلم حدثنا وهيب حدثنا ابن طاوس عن أبيه

عن ابن عباس رضي الله عنهما قال

كانوا يرون أن العمرة في أشهر الحج من الفجور في الأرض وكانوا يسمون المحرم صفرا ويقولون إذا برا الدبر وعفا الأثر حلت العمرة لمن اعتمر قال فقدم رسول الله ﷺ وأصحابه رابعة مهلين بالحج وأمرهم النبي ﷺ أن يجعلوها عمرة قالوا يا رسول الله أي الحل قال الحل كله

البخاري 3832صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Virtues of the Ansar
Chapter
Days of Jahiliyyah
Numbering
Darussalam 3832
Bukhari 3832