Hazrat Ata was asked that if a person performs Umrah in a month other than the months of Hajj, is Hadi (sacrificial animal) obligatory upon him? He replied that Hadi is not obligatory upon him, and indeed the Companions used to offer Hadi, and the year when the polytheists prevented the Noble Prophet (peace and blessings be upon him), that year he (peace and blessings be upon him) also offered a sacrifice. (The narrator asked) Did the Prophet (peace and blessings be upon him) assume Ihram for Umrah? He replied, yes, and a treaty was made with those polytheists on the condition that these people would come the following year, and I have also seen Amir Muawiyah performing Umrah and offering a sacrifice outside the months of Hajj.

16178 - And I saw Muawiya slaughtering a camel during ‘umrah outside the months of Hajj (1).