Sunan an-Nasa'i, Volume 4, Book 27, Hadith 3422 (DarusSalam) ⓘ
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."
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 .
also referenced under: Hadith 3393 (Reference) & Book 27, Hadith 5 (In-Book)