Abd al-Rahman bin Yazid narrates from Sayyiduna Ibn Mas'ud (may Allah be pleased with him) that, in explaining the verse "Then divorce them for their waiting period" [Surah al-Talaq: 1], he said: "That is, in a state of purity, without intercourse."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9575