Musannaf Ibn Abi Shayba 3:1936

Hushaym narrated to us, he said: Mughira informed us, from Ibrahim, that he used to say regarding the person in a state of major ritual impurity (junub): If he hears the prostration (verse), he should perform ghusl (ritual bath), then recite it and prostrate with it. And if he does not know it well, he should recite another (verse) and then prostrate.