حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ أَبِي أُمَامَةَ بْنِ سَهْلِ بْنِ حُنَيْفٍ، أَنَّهُ قَالَ دَخَلَ زَيْدُ بْنُ ثَابِتٍ الْمَسْجِدَ فَوَجَدَ النَّاسَ رُكُوعًا فَرَكَعَ ثُمَّ دَبَّ حَتَّى وَصَلَ الصَّفَّ ‏.‏

Yahya related to me from Malik from Ibn Shihab that Abu Umama ibnSahl ibn Hunayf said, "Zayd ibn Thabit entered the mosque and foundthe people in ruku, so he went into ruku and then moved slowly forwarduntil he reached the row." Translation Not Available

Book Ref: Muwatta Imam Malik Book 9 Hadith 398
Web Ref:  Muwatta Imam Malik Book 9 Hadith 67