عَنْ أَبِي جَعْفَرٍ (ع) قَالَ بَيْنَا رَسُولُ اللٌّهِ (ص) جَالِسٌ فِي الْمَسْجِدِ إِذْ دَخَلَ رَجُلٌ فَقَامَ يُصَلِّي فَلَمْ يُتِمَّ رُكُوعَهُ وَ لاَ سُجُودَهُ فَقَالَ (ص) نَقَرَ كَنَقْرِ الْغُرَابِ لَئِنْ مَاتَ هٌذَا وَ هٌكَذَا صَلاَتُهُ لَيَمُوتَنَّ عَلى غَيْرِ دِيـنِي.
Imam Al-Baqir (peace be upon him) narrates: One day the Messenger of Allah (peace be upon him and his progeny) was seated in the mosque when a person entered and began praying, but in a manner such that neither did he perform his ruku’ (bowing), nor his sujood (prostration) in a correct manner. Observing this, the Messenger of Allah commented: “(This person) pecks as a crow pecks. Should he die and the state of his prayers be as they are now, he shall surely not die upon my religion.”
Al-Mahajjatul Baidha, Volume 1, Page 34