Brusthom Ziamani claimed it was a coincidence he was carrying the last speech of a suicide bomber in his pocket when attacked a prison officer at HMP Whitemoor.
The 25-year-old Muslim convert admitted giving the transcript to his co-defendant, Baz Hockton, and said it was from one of 64 videos from an illicit SD card.
Mr Ziamani said he put the paper in his pocket after it was returned and had “forgotten about it” when the pair attacked a prison officer while shouting “Allahu akbar” and wearing fake suicide vests.
“It was a speech from a French Isis jihadi that I translated into English,” he told the Old Bailey on Friday.
“At the same time I was taking notes I improved my French with it as well.”
Asked by prosecutor Annabel Darlow QC why he would write out the last words of Isis suicide bombers, Mr Ziamani replied: “I’m not saying I was agreeing with it, I was just translating it.
“He was speaking eloquent French as well, it’s very rare that I hear French stuff in this country on TV.”
The court heard that the defendant spoke French as his first language as a child, because his parents had moved to Britain from the Democratic Republic of the Congo.
Ms Darlow told Mr Ziamani: “It’s rubbish, the idea that you wrote out the last words of a suicide bomber to practice your French translation skills and had it in your pocket while carrying out an attack wearing a suicide belt by chance.”
But Mr Ziamani denied the prosecutor’s allegations and maintained he had “loads of translations” in his cell.
The court heard the SD card Mr Ziamani said he had used was not found in his cell. He told jurors he had flushed it down a toilet because it was contraband.
The former gangster, who was jailed in 2015 for plotting to behead a British soldier, has denied the HMP Whitemoor attack was terrorism.
He and Mr Hockton also both deny attempting to murder prison officer Neil Trundle using homemade weapons.
While being cross-examined on Friday, Mr Ziamani claimed he had made two metal weapons previously after being attacked in prison and always carried them in his pockets.
He said he was holding a third weapon during the attack to strengthen his fist while punching his victim, because he had sprained his wrist.
Ms Darlow accused him of making the weapons specifically for the attack on 9 January and questioned how, if he carried them all the time, they had not been picked up by frequent body searches or metal detectors.
Mr Ziamani claims he mounted the attack to force prison authorities to move him out of HMP Whitemoor, because he was unhappy with his treatment there.
He said Mr Hockton helped him because they were friends, and had met outside jail in 2013 through gang associations in London.
Mr Ziamani claimed the fake suicide vests they both wore were Mr Hockton’s idea, and that they wanted to “get the officers scared, keep them away from us that day and to try and freak them out”.
He admitted shouting “Allahu akbar” during and after the attack, but said it was a declaration of faith rather than an ideological statement.
The defendant also admitted giving Mr Hockton, who converted to Islam in prison, extremist material but insisted it was “because he was studying Islam”.
“I didn’t tell him what to do with it - he asked for material and I gave him loads,” Mr Ziamani added.
He told jurors that he believed in jihad in the meaning of “struggle”, but not “with taking up arms and just killing anyone”
Mr Ziamani denied that his aim was to become a martyr during the attack at HMP Whitemoor, or that he intended to murder the prison officer or do him “really serious harm”.
The court heard Mr Trundle, a prison officer for 14 years, was known to be “kind and helpful” and had no negative dealings with either defendant in the past.
Jurors were told the defendants attacked him from behind after trying to push him into a storage cupboard, raining down blows until they were physically restrained by other officers.
Jurors were shown photos of Mr Trundle’s injuries, including lacerations to his head, face, arms, back, chest and shoulder.
Both men deny charges of attempted murder but Mr Hockton had admitted an alternative charge of wounding with intent to cause grievous bodily harm.
Mr Ziamani admits charges of assault against another prison officer and a nurse.
The trial continues.