Groaning: by saying 'Oh', this invalidates the prayer, unless the person is sick and cannot help groaning and moaning; because his moaning then is like sneezing if it results in letters. Ibn Abbas, may Allah be pleased with him, said that the Prophet, peace be upon him, said: ((Blowing in prayer is speech)), in Musannaf Ibn Abi Shaybah 2: 67, and Musannaf Abdul Razzaq 2: 189, and its chain is authentic. See: I'la al-Sunan 5: 51. And from Abu Huraira, may Allah be pleased with him: he said: ((Blowing in prayer is speech)), in Musannaf Abdul Razzaq 2: 189. See: Fath Bab al-Inayah 1: 302.