Abdullah bin Abbas reported,
The Messenger of Allah ﷺ cursed the man who marries a divorced woman to make her lawful for her former husband, and the one for whom she is made lawful.
Ibn Majah 1934
Sahihحدثنا محمد بن بشار حدثنا أبو عامر عن زمعة بن صالح عن سلمة بن وهرام عن عكرمة
عن ابن عباس قال
لعن رسول الله ﷺ المحلل والمحلل له
No references are available.
[Sahih] Zama has already been mentioned, no. 326. His hadith has a hasan corroborating narration in Ahmad and others from the hadith of Abu Hurairah 
2/323, and Ibn Jarud graded it sahih, no. 684, and Bukhari graded it hasan (Talkhis Habir 3/(170)). The hadith has many corroborating narrations, some of which I mentioned in Nail Maqsud, no. 2076. It is established that the aforementioned practice of making it lawful was denounced by Umar, Uthman, Ibn Umar and others, may Allah be pleased with them all.