'Ark of the Testimony' in the Bible

When the camp sets forward, Aaron shall go in, and his sons, and they shall take down the veil of the screen, and cover the ark of the testimony with it.

And when Moses went into the tent of meeting to speak with him, then he heard the Voice speaking to him from above the mercy-seat that was upon the ark of the testimony, from between the two cherubim, and he spoke to him.