Shuba reported,
I heard Ibn Abbas being questioned by a man who said, "I used to have relations with a woman, doing with her what Allah 
had forbidden me. Then Allah granted me repentance, and I wanted to marry her. But some people said, 'A fornicator marries none but a fornicatress.'"Ibn Abbas replied, "That verse does not apply to this situation. Marry her, and whatever sin there may be is on me."
Azami 12839
Hasanعن شعبة مولى ابن عباس قال
سمعت ابن عباس ورجل سأله، فقال: إني كنت ألم بامرأة آتي منها ما حرم الله عز وجل علي، فرزقني الله من ذلك توبة، فأردت أن أتزوجها، فقال أناس: إن الزاني لا ينكح إلا زانية، فقال ابن عباس: ليس هذا في هذا، انكحها، فما كان من إثم فعلي.
No references are available.
Ibn Abu Shayba narrated it in Musannaf (17200), Ibn Jareer in his Tafsir (17/153), and Ibn Abu Hatim in his Tafsir (8/2521), all of them through the route of Ibn Abu Dhib, who said, "I heard Shubah, the freedman of Ibn Abbas, say," and then he related it.Its chain is hasan because of Shubah, the freedman of Ibn Abbas, for he is hasan al-hadith.