كتاب 9
9  
Book 9
(9)
Chapter 9
(9)
باب 9
Muwatta Malik 400
Yahya related to me from Malik that he had heard that Abdullah ibn Masud used to move forward while in ruku.
وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عَبْدَ اللَّهِ بْنَ مَسْعُودٍ، كَانَ يَدِبُّ رَاكِعًا ‏.‏
Reference : Muwatta Malik 400
In-book reference : Book 9, Hadith 34578
USC-MSA web (English) reference : Book 7, Hadith 400
  (deprecated numbering scheme)