Sahih Al Bukhari Hadith Number 1563

Narrated Marwan bin Al-Hakam: I saw `Uthman and `Ali. `Uthman used to forbid people to perform Hajj-at-Tamattu` and Hajj-al- Qiran (Hajj and `Umra together), and when `Ali saw (this act of `Uthman), he assumed Ihram for Hajj and `Umra together saying, “Lubbaik for `Umra and Hajj,” and said, “I will not leave the tradition of the Prophet (peace be upon him) on the saying of somebody.”