Tamattu‘ in Hajj is when the pilgrim assumes Ihrām for ‘Umrah along with his Hajj. So, when he comes to Makkah and performs ‘Umrah and completes it, he may end his Ihrām and enjoy all that is lawful until the rituals of Hajj begin, on the 8th of Dhul-Hijjah. Some of the Companions did it along with the Prophet (may Allah's peace and blessings be upon him) during the Farewell Hajj. In this Hadīth, ‘Imrān ibn Husayn (may Allah be pleased with him) said to Mutarrif ibn ‘Abdullāh ibn ash-Shikhkhīr: "I will narrate to you a Hadīth today by which Allah will benefit you after today" i.e., Allah will benefit you by it for the rest of your life, given the Fiqh and religious knowledge contained therein. And know that the Prophet (may Allah's peace and blessings be upon him) permitted some of his wives to perform ‘Umrah during the first ten days of Dhul-Hijjah, before the commencement of the Hajj rituals. He meant to say to him: The Prophet (may Allah's peace and blessings be upon him) made some of his wives perform ‘Umrah with Tamattu‘ before Hajj. In the version by Al-Bukhāri: "We performed it along with the Messenger of Allah (may Allah's peace and blessings be upon him)." Then, he (may Allah be pleased with him) informed that nothing of the Qur’an forbade Tamattu‘ in Hajj and abrogate this ruling; also, the Prophet (may Allah's peace and blessings be upon him) did not prohibit Tamattu‘ in Hajj till he passed away. But, after his death, "everyone held the opinion he liked." In a version: "A man held the opinion he liked" i.e., after the Prophet's death, some people adopted an opinion not supported by proof from the Qur’an or the Sunnah. By this statement, he was referring to ‘Umar ibn al-Khattāb (may Allah be pleased with him), for he was the one who forbade Mut‘ah in Hajj. His forbiddance, however, was not meant as prohibition. Rather, he intended to encourage people to perform Hajj of Ifrād only, since ‘Umrah is available all year long. So, ‘Umar (may Allah be pleased with him) did not prohibit Tamattu‘ altogether. He only wanted to encourage Ifrād. In a version by Muslim, ‘Umar (may Allah be pleased with him) said: "So, separate your Hajj from your ‘Umrah. This makes your Hajj more complete and your ‘Umrah more complete." This points to his forbiddance of Tamattu‘ in Hajj. Perhaps he saw this as more perfect for both acts of worship, or he probably based his opinion on another meaning, such that people should not cease to come to the House; rather, they should frequent it, coming once for Hajj and another time for ‘Umrah - and Allah knows best. The Hadīth shows that the Companions engaged in Ijtihād regarding religious rulings, and some of them objected to others citing religious texts. It demonstrates the validity of Tamattu‘ in Hajj, as the Prophet (may Allah's peace and blessings be upon him) made some of his wives observe it..