Muwatta Malik, Book 9, Hadith 68 (USC-MSA) ⓘ
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 .
also referenced under: Book 9, Hadith 399 (In-Book)