Exodus 25:21
ESV
And you shall put the mercy seat on the top of the ark, and in the ark you shall put the testimony that I shall give you.
NIV
Place the cover on top of the ark and put in the ark the tablets of the covenant law that I will give you.
NASB
Then you shall put the atoning cover on top of the ark, and in the ark you shall put the testimony which I will give to you.
CSB
Set the mercy seat on top of the ark and put the tablets of the testimony that I will give you into the ark.
NLT
Place inside the Ark the stone tablets inscribed with the terms of the covenant, which I will give to you. Then put the atonement cover on top of the Ark.
KJV
And thou shalt put the mercy seat above upon the ark; and in the ark thou shalt put the testimony that I shall give thee.
NKJV
You shall put the mercy seat on top of the ark, and in the ark you shall put the Testimony that I will give you.
What does Exodus 25:21 mean?
The "ark of the covenant" is a wooden box gilded with gold (Exodus 25:10–11). This box includes rings so it can be transported with poles (Exodus 25:12–15). A main purpose of this golden chest is to store the stone tablets which record God's covenant with Israel (Exodus 19:5–6; 25:16; 31:18). It will also be used to keep a jar of manna (Exodus 16:33–34) and Aaron's staff (Numbers 17:10).The ark's lid is a solid piece of metal which includes two winged cherubim (Exodus 25:17–19). These angel-like creatures extend their wings over the lid to form a "mercy seat." The mercy seat serves several purposes beyond being a lid. It will be the physical place from which God speaks (Exodus 25:22; Numbers 7:89). It will also receive blood meant for atonement (Leviticus 16:14–16) during a yearly remembrance.