Key হজ্জ dhikr includes the তালবিয়াহ (from ইহরাম to stoning), the আরাফাত declaration of tawheed, takbirat al-Tashreeq on the 11th-13th, and personal dua during তাওয়াফ.
Dhikr (remembrance of Allah) is the spiritual essence of হজ্জ, transforming physical actions into acts of deep worship. The most important dhikr during হজ্জ is the তালবিয়াহ: 'Labbayk Allahumma labbayk, labbayk la sharika laka labbayk, innal hamda wan-ni'mata laka wal-mulk, la sharika lak.' This should be recited frequently and aloud (for men) from the moment of entering ইহরাম until the stoning of জামারাত al-Aqaba on the 10th.
At আরাফাত, নবী করীম (সাল্লাল্লাহু আলাইহি ওয়া সাল্লাম) said: 'The best dua is on the Day of আরাফাত, and the best thing that I and the prophets before me said is: La ilaha illa Allahu wahdahu la sharika lah, lahul mulku wa lahul hamdu wa huwa ala kulli shay'in qadir.' During the days of Tashreeq (11th-13th), the takbirat of Tashreeq are prescribed: 'Allahu Akbar, Allahu Akbar, la ilaha illa Allah, Allahu Akbar, Allahu Akbar, wa lillahil hamd.' During তাওয়াফ, there is no specific prescribed dhikr — scholars advise making personal dua, reciting কুরআন, or any dhikr that moves your heart. Between the Yemeni corner and the হাজরে আসওয়াদ, the sunnah dua is: 'Rabbana atina fid-dunya hasanah wa fil-akhirati hasanah waqina adhab al-nar.'
Source: Sunan al-Tirmidhi; Muwatta of Imam Malik; Sahih Muslim