Dhū al-Ḥijjah’s first ten days are the most auspicious days of the year. Allāh’s Messenger (ﷺ) said: “There are no days in which righteous deeds are more beloved to Allāh than these ten days. They said: “Not even jihād for Allāh’s sake?” He (ﷺ) said: “Not even jihād for Allāh’s sake unless a man goes out himself for jihād taking his wealth with him and does not return with anything.” (Reported by al-Bukhārī with this wording) Consequently, the Messenger (ﷺ) legislated Allāh’s remembrance during this time. He (ﷺ) said: “There are no days that are greater before Allāh nor in which good deeds are more beloved to Him than these ten days, so recite the taḥlīl [i.e. saying Lā ilāha illā-Allāh], the takbīr [i.e. saying Allāhu Akbar], and the taḥmīd [i.e. saying Alhamdulillāh] frequently.” (Reported by Imām Aḥmad with this wording, and Shaykh Aḥmad Shākir authenticated it.)

As a result, Ibn al-Qayyim (رحمه الله) stated: “Making the takbīr, the tahlīl, and the taḥmīd is the best form of worship performed during the first ten days of Dhū al-Ḥijjah.” (Madārij al-Sālikīn, vol. 1, pg. 110)

As a consequence, the Salaf hastened to engage frequently in Allāh’s remembrance during this time. Maymūn ibn Mihrān (رضي الله عنه), from the tabiʿīn said: “I found the people making the takbīr frequently during the first ten days of Dhū al-Ḥijjah so much so that it resembled waves.” (Fatḥ al-Bārī, vol. 9, pg. 9)

The men from amongst the Salaf would also remember Allāh loudly. Imām al-Bukhārī (رحمه الله) reported: “Ibn ʿUmar (رضي الله عنه) and Abū Hurayrah (رضي الله عنه) would make the takbīr while going to the market place on the ten days of Dhū al-Ḥijjah. The people then followed suit.” (Ṣaḥīḥ al-Bukhārī, vol 2, pg 20)

As for those who say that making the takbīr during Dhū al-Ḥijjah’s first ten days is an innovation, then this opinion is clearly wrong since making the takbīr is a well established Sunnah. Shuʿbah (رضي الله عنه) reported: “I asked Al-Ḥakam (رضي الله عنه) and Ḥammād (رضي الله عنه) about the takbīr during Dhū al-Ḥijjah’s first ten days. They responded: ‘Avoid  making it, for it is an innovation.’” (Fatḥ al-Bārī, vol. 9, pg. 9) 

Ibn Rajab (رحمه الله), commenting on this report, said: “Some scholars held an extreme opinion, but they only considered making the takbīr an innovation because the prophetic traditions about this did not reach them.” (Fatḥ al-Bārī, vol. 9, pg. 9)

Therefore, engaging in Allāh’s remembrance frequently and audibly during Dhū al-Ḥijjah’s first ten days is highly recommended. Regrettably, the abandonment of this sunnah started very early. Maymūn ibn Mihrān (رضي الله عنه) himself said: “Verily, the people have fallen short as they have abandoned the takbīr.” (Fatḥ al-Bārī, vol. 9, pg. 9)

The contemporary scholar Shaykh al-ʿUthaymīn (رحمه الله) also stated that this sunnah is neglected. He said: “Muslims spend Dhū al-Ḥijjah’s first ten days as they would spend any other day. Not only do they fail to recite extra Qurʾān, but they also fail to perform any other supplementary forms of worship. As for those who chose to make the takbīr, then they rarely say it.” (Al-Sharḥ al-Mumtiʿ, vol. 6, pg. 470) 

Therefore, we should try to revive this Sunnah. Engage in Allāh’s remembrance frequently and audibly during Dhū al-Ḥijjah’s first ten days. And all success lies with Allāh.