Ibn al-Qayyim رحمه الله: “That which is more virtuous during the (first) ten days of Dhul-Hijjah, is to increase in worship, especially in Takbīr (saying Allāhu Akbar), Tahlīl (saying Lā Ilāha Illa Allāh), and Tahmīd (saying Alhamdu Lillāh), for that is superior than the Jihād which is not Fardh 'Ayn (obligatory upon every individual)." [Madārij As-Sālikīn | 1/89]