Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said concerning the saying of Allah Almighty: "of your wives with whom you have had intercourse" [Surah al-Nisa: 23]: (It means) your wives with whom you have had intercourse. Al-dukhul is nikah, and by nikah is meant intercourse; likewise al-mass, al-lams and al-ifda' are in the sense of intercourse. And Tawus (may Allah have mercy on him) said that al-dukhul means intercourse.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13919