قَالَ أَبُو عَبْدِ اللَّهِ ع فِي الرَّجُلِ إِذَا أَدْرَكَ الْإِمَامَ وَ هُوَ رَاكِعٌ فَكَبَّرَ وَ هُوَ مُقِيمٌ صُلْبَهُ ثُمَّ رَكَعَ قَبْلَ أَنْ يَرْفَعَ الْإِمَامُ رَأْسَهُ فَقَدْ أَدْرَكَ.
“Abu ‘Abd Allah (a.s.), has said, ‘If a man finds the Imam in Ruku‘ (bowing down on one’s knees), says Takbir (Allah is great beyond description) while his back is straight and performs Ruku‘ before the Imam raises his head, has joined for one Rak‘at.’”