Muwatta Malik 1146

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ رَبِيعَةَ بْنِ أَبِي عَبْدِ الرَّحْمَنِ، أَنَّ الْقَاسِمَ بْنَ مُحَمَّدٍ، وَعُرْوَةَ بْنَ الزُّبَيْرِ، كَانَا يَقُولاَنِ فِي الرَّجُلِ يَكُونُ عِنْدَهُ أَرْبَعُ نِسْوَةٍ فَيُطَلِّقُ إِحْدَاهُنَّ الْبَتَّةَ أَنَّهُ يَتَزَوَّجُ إِنْ شَاءَ وَلاَ يَنْتَظِرُ أَنْ تَنْقَضِيَ عِدَّتُهَا ‏.‏

Yahya related to me from Malik from Rabia ibn Abi Abd ar-Rahman that al-Qasim ibn Muhammad and Urwa ibn az-Zubayr said that a man who had four wives and then divorced one of them irrevocably, could marry straightaway if he wished, and he did not have to wait for the completion of her idda

Reference

Muwatta Malik 1146

In-book

Book 28, Hadith 56