It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "A prayer in whose bowing and prostration a man does not level his back is of no avail."
Only Yahya bin Abi Bukayr narrated it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2572