What formulation is required from the original witness to permit a third party to testify about their testimony?
General Chapter
Al-Mughni
Book of Testimonies
Primary text
The original witness must request the third party to testify about their testimony. This is achieved by the original witness saying, 'Testify concerning my testimony that I testify that so-and-so owes so-and-so such-and-such,' or that he acknowledged such-and-such before him. If a hearer witnesses another requesting testimony from the first, the hearer may testify on that basis.
Supporting text
Abu Hanifa holds that the third party may not testify unless the original witness explicitly requests testimony concerning his testimony. Ahmad stated that testimony only occurs when the witness specifically asks you to bear witness; otherwise, hearing him speak is merely conveying information (hadith).