Divrey Hayamim Bais 22:11

But Yehoshavat Bat HaMelech, took Yoash ben Achazyahu, and stole him away from among the Bnei HaMelech that were being murdered, and put him and his nurse in a cheder hamittot (bedroom). So Yehoshavat Bat HaMelech Yehoram, the isha of Yehoyada HaKohen, (for she was the achot of Achazyahu), hid him from Atalyah, so that she slaughtered him not.