Because of the saying of Allah, the Mighty and Majestic: "They (the believing women) are not lawful for them (the disbelievers), nor are they (the disbelievers) lawful for them." [Surah al-Mumtahanah: 10]
And because of the saying of Allah Almighty: "And do not hold on to the marriage ties of disbelieving women." [Surah al-Mumtahanah: 10]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / Q14061