The third book: Refutation of the Jahmites.

The editor, Dr. Yūsuf al-Wābil—may Allah preserve him—states, 169/1–170:

Sources relied upon by Ibn Baṭṭah in al-Ibānah:

Imām Ibn Baṭṭah was an Atharī scholar who built his arguments on the Book, the Sunnah, and the statements of the Companions and the Tābiʿīn, indeed on the collective legacy of the early generations. For that reason he was markedly influenced by the scholars who preceded him, most notably Imām Aḥmad ibn Ḥanbal. We therefore find him transmitting many of Aḥmad’s words with an unbroken chain of narration back to the Imām, making these reports—after the Qur’an, the Sunnah, and the sayings of the Companions (may Allah be pleased with them)—a principal evidentiary foundation.

The bulk of the traditions he cites already appear in the works of earlier scholars from Ahl al-Sunnah; Ibn Baṭṭah reproduces them with continuous isnāds to the authors of those books. Among such works is Imām Aḥmad’s Refutation of the Jahmites.

The editor—may Allah protect him—lists other sources that Ibn Baṭṭah drew upon in al-Ibānah as well.

Ibn Baṭṭah, may Allah have mercy on him, quoted extensively from Imām Aḥmad’s epistle; see 86/2–89, which in Dr. ʿAmīrah’s edition corresponds to 101–104, and 157/2, 160, corresponding to pp. 106–108 of Dr. ʿAmīrah’s text.

Likewise, consult 166/2–167, which in al-Radd matches pp. 112–113 of Dr. ʿAmīrah’s edition.