Muwatta Imam Malik Book of Shortening the Prayer, Hadith 68

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 .