Musannaf Ibn Abi Shayba 13:2647

Abu Bakr narrated to us, he said: Abd al-Wahhab al-Thaqafi narrated to us, from Ja'far ibn Muhammad, who said: Al-Qasim ibn Muhammad bore witness to a testimony before Aban ibn Uthman for a man. The man began to remind him of something regarding his testimony, and he (Al-Qasim) said: "I do not remember it, and I do not recall anything except this." Then he went out, and he remembered while the people were sitting. He said: "This man asked me about something in my testimony that I did not remember for him, and I have now remembered it. And I testify that what they said is the truth, and I testify to it."