Hadith.1203 - Ammar al-Sabati narrated from Imam Jafar ibn Muhammad Al-Sadiq (as) who said
"I asked him about a man who, while praying behind an Imam, forgets to say the tasbih (glorification) during Sujood (prostration) or ruku' (bowing) or forgets to say something between the two prostrations."
Imam (as) said: "There is no obligation upon him (no penalty)."