Arabic
سُبْحَانَ اللَّهِ وَالْحَمْدُ لِلَّهِ وَلاَ إِلَهَ إِلاَّ اللَّهُ وَاللَّهُ أَكْبَرُ
Meaning
Glory be to Allah, praise be to Allah, there is no deity but Allah, and Allah is the Greatest. (These four are the most beloved words to Allah; the first ten days of Dhul-Hijjah are the best days for righteous deeds.)
Source
HadithMuslim 2137 (en sevimli sözler); Zilhicce'nin ilk on gününde amelin fazileti: Bukhari 969