'Ark of the Testimony' in the Bible

When the camp is about to travel, Aaron and his sons are to come and take down the veil of the curtain and cover the Ark of the Testimony with it.

When Moses entered the Tent of Meeting to speak with the L ORD, he heard a voice speaking to him above the Mercy Seat over the Ark of the Testimony. He spoke to him from between the two cherubim.