214. Jabir (RA), said: Whenever we went up a hill we would say:

اللهُ أَكْـبَر

Allaahu 'Akbar 

Allah is the Most Great 

And when we descended we would say:

سُبْـحانَ الله  

Subhaanallaah 

Glory is to Allah.

Reference: Al-Bukhari, cf. Al-Asqalani, Fathul-Bari 6/135.