Hadith 501690
Chapter 3: Prayer - كتاب الصلاة
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ أَبِي نُعَيْمٍ، وَهْبِ بْنِ كَيْسَانَ عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ، أَنَّهُ كَانَ يُعَلِّمُهُمُ التَّكْبِيرَ فِي الصَّلاَةِ . قَالَ فَكَانَ يَأْمُرُنَا أَنْ نُكَبِّرَ كُلَّمَا خَفَضْنَا وَرَفَعْنَا .
Yahya related to me from Malik from Abu Nuaym Wahb ibn Kaysan that Jabir ibn Abdullah used to teach them the takbir in the prayer. Abu Nuaym said, "He used to tell us to say 'Allah is greater' whenever we lowered or raised ourselves."
Reference Muwatta Malik 501690
USC-MSA web (English) reference : Book 3, Hadith 22