Muwatta Imam Malik Book of Prayer, Hadith 34

Yahya related to me from Malik that Yazid ibn Ruman said, "I used to pray next to Nafi ibn Jubayr ibn Mutim and he would nudge me to prompt him while we were praying."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَزِيدَ بْنِ رُومَانَ، أَنَّهُ قَالَ كُنْتُ أُصَلِّي إِلَى جَانِبِ نَافِعِ بْنِ جُبَيْرِ بْنِ مُطْعِمٍ فَيَغْمِزُنِي فَأَفْتَحُ عَلَيْهِ وَنَحْنُ نُصَلِّي .