Musannaf Ibn Abi Shayba 23:137

Al-Fadl ibn Dukayn narrated to us, he said: Hisham ibn Sa’id narrated to us, from Zayd ibn Aslam, who said: The people of this religion must have four things: entering into the call of Islam. And there must be faith and belief in Allah, and in the messengers, the first of them and the last of them, and in Paradise and the Fire, and in the resurrection after death. And there must be that you perform a deed by which you verify it. And there must be that you acquire knowledge by which you improve your deed. Then he recited: "And indeed, I am the Perpetual Forgiver of whoever repents and believes and does righteousness and then continues to be guided."