Yahya related to me from Malik that Abdullah ibn Dinar said, "I heard Abdullah ibn Umar recite from the Qur'an, 'Prophet! When you divorce women, divorce them at the beginning of their idda.'"
Malik said, "He meant by that, to make one pronouncement of divorce at the beginning of each period of purity."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، أَنَّهُ قَالَ سَمِعْتُ عَبْدَ اللَّهِ بْنَ عُمَرَ، قَرَأَ {يَا أَيُّهَا النَّبِيُّ إِذَا طَلَّقْتُمُ النِّسَاءَ فَطَلِّقُوهُنَّ} لِقُبُلِ عِدَّتِهِنَّ . قَالَ مَالِكٌ يَعْنِي بِذَلِكَ أَنْ يُطَلِّقَ فِي كُلِّ طُهْرٍ مَرَّةً .