Exodus 25:21
Set the mercy seat on top of the ark and put the testimony that I will give you into the ark.
Exodus 26:34
                            Put the mercy seat on the ark of the testimony in the most holy place.
Exodus 25:16-17
                            Put the tablets of the testimony that I will give you into the ark.
Romans 10:4
                            For Christ is the end
Treasury of Scripture Knowledge
Summary
                            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.                        
                    Mercy seat
In
General references
Bible References
Mercy seat
                                        Exodus 25:17                                        
                                                                                                                                Make a mercy seat of pure gold, 45 inches long and 27 inches wide.   
                                    
                                        Exodus 26:34                                        
                                                                                                                                Put the mercy seat on the ark of the testimony in the most holy place.  
                                    
                                        Romans 10:4                                        
                                                            
                        For Christ is the end of the law for righteousness to everyone who believes.    
                                    In
                                        Exodus 25:16                                        
                                                            
                        Put the tablets of the testimony that I will give you into the ark.  
                                    General references
                                        Exodus 16:34                                        
                                                                                                                                As the Lord commanded Moses, Aaron placed it before the testimony to be preserved.  
                                    
                                        Exodus 37:6                                        
                                                                                                                                He made a mercy seat of pure gold, 45 inches long and 27 inches wide.  
                                    
                                        Revelation 15:5                                        
                                                            
                        After this I looked, and the heavenly sanctuary—the tabernacle of testimony—was opened.