أَخْبَرَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنِ الْحَكَمِ، قَالَ سَمِعْتُ مُجَاهِدًا، يُحَدِّثُهُ عَنِ ابْنِ عَبَّاسٍ، فِي قَوْلِهِ عَزَّ وَجَلَّ ‏{‏ يَا أَيُّهَا النَّبِيُّ إِذَا طَلَّقْتُمُ النِّسَاءَ فَطَلِّقُوهُنَّ لِعِدَّتِهِنَّ ‏}‏ قَالَ ابْنُ عَبَّاسٍ رضى الله عنه قُبُلِ عِدَّتِهِنَّ ‏.‏

It was narrated from Ibn 'Abbas, concerning the saying of Allah, the Mighty and Sublime: "O Prophet! When you divorce women, divorce them at their 'Iddah (prescribed periods)." Ibn 'Abbas, may Allah be pleased with him, said: "Before their 'Iddah elapses." Translation Not Available

Book Ref: Sunan An Nisai Book 27 Hadith 3393
Web Ref:  Sunan An Nisai Vol 4 Book 27 Hadith 3422