Sahih al-Bukhari 2993

Arabic

حَدَّثَنَا مُحَمَّدُ بْنُ يُوسُفَ، حَدَّثَنَا سُفْيَانُ، عَنْ حُصَيْنِ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ سَالِمِ بْنِ أَبِي الْجَعْدِ، عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ ـ رضى الله عنهما ـ قَالَ كُنَّا إِذَا صَعِدْنَا كَبَّرْنَا، وَإِذَا نَزَلْنَا سَبَّحْنَا‏.‏

English translation

Narrated Jabir bin `Abdullah:Whenever we went up a place we would say, "Allahu--Akbar (i.e. Allah is Greater)", and whenever we went down a place we would say, "Subhan Allah

Reference: Sahih al-Bukhari 2993, Book of Fighting for the Cause of Allah (Jihaad). English translation by Dr. Muhammad Muhsin Khan.