What is the ruling if a Dhimmi issues a Dhihar against his wife and subsequently both he and his wife embrace Islam?

Primary text

If a Dhimmi issues Dhihar against his wife, and subsequently both he and his wife embrace Islam, the Dhihar penalty (Kaffarah) is obligatory upon him based on the Quranic verse concerning those who pronounce Dhihar against their wives ({Walladhina yuzahiruna min nisa'ihim} [Al-Mujadilah: 3]).