Reference: Fataawa Ramadhaan – Volume 2, Page 763, Fatwa No.776
Majmoo’ Fataawa Shaykh al-Islaam Ibn Taymiyyah – Volume 25, Pages 287
Question: Regarding the [first] ten [days and nights] of Dhul-Hijjah and the [last] ten [days and nights] of Ramadhaan, which of the two are superior?
Response: The [first] ten days of Dhul-Hijjah are superior to the [last] ten days of Ramadhaan and the last ten nights of Ramadhaan are superior to the [first] ten nights of Dhul-Hijjah. As for the [last] ten nights of Ramadhaan then they are the nights of activity (worship), which the Prophet (sal-Allaahu ‘alayhi wa sallam) used to spend them all awake [in worship]. And within them is Laylatul-Qadr which is better than a thousand months. So whoever responds with other than this explanation then it is not possible he has adduced with the correct proof.