Why was the first tenth of Dhul-Hijjah specifically designated for Takbir?

Allah Almighty has specifically honored the first ten days of Dhul-Hijjah with abundant فضْل (virtue), as stated in the Hadith narrated by Ibn Abbas (may Allah be pleased with them both) from the Prophet (peace and blessings be upon him): “There are no days in which righteous deeds are more beloved to Allah than these ten days.” They (the companions) asked, “O Messenger of Allah, not even Jihad in the way of Allah?” He replied, “Not even Jihad in the way of Allah, except for a man who goes out with his life and his wealth and does not return with any of them.” Therefore, one should increase in righteous deeds, especially the remembrance of Allah Almighty during these days, for it is among the best, purest, and highest in rank of all deeds.