Yahya related to me from Malik from Thawr ibn Zayd ad-Dili thatAllah, the Blessed, the Exalted, sent down about a man who divorcedhis wife and then returned to her while he had no need of her and didnot mean to keep her so as to make the idda period long for her bythat in order to do her harm, "Do not retain them by force, totransgress. Whoever does that has wronged himself." (Sura 2 ayat 231).Allah warns them by that ayat.
USC-MSA web (English) reference: Book 29, Hadith 81
Arabic reference: Book 29, Hadith 1243