[6/1555] al-Kafi: Abu Ali al-Ash’ari from Muhammad b. Abd al-Jabbar from Safwan b. Yahya from Ya’qub b. Shuayb from Abi Abdillah عليه السلام who said
My father صلوات الله عليه used to say: Qul Huwa l-Llāhu Aḥad is a third of the Qur’an, and, Qul Yā Ayyuhā l-Kāfirūn is a fourth of the Qur’an