Sayyiduna Abdullah (may Allah be pleased with him) said, in explanation of the Qur'anic verse "So divorce them at their prescribed period": Divorce them while they are in a state of purity, during a period of purity in which you have not had intercourse with them.
Hadith Referenceمصنف ابن ابي شيبه / كتاب الجنة / 36943
Hadith Takhrij(مصنف ابن ابي شيبه: ترقيم سعد الشثري ، ترقيم محمد عوامة 18021)