What Did the Ark of the Covenant Contain (Hebrews 9:4)?
I Kings 8:9 and Hebrews 9:4 do seem to contradict each other. One verse says that only the two stone tablets inscribed with the ten commandments were in the ark. The other verse lists several additional objects which apparently were also in the ark. However, God's Word does not contradict itself.
The original Greek word translated "in which" (wherein, KJV) in Hebrews 9:4 is hou. Biblical lexicons say that hou means "at which place." Hou is a general word that does not necessarily mean "wherein," "within," or "in." It simply means "in the same location as."
With this in mind, notice Deuteronomy 31:24-26:
So it was, when Moses had completed writing the words of this law in a book [not the Ten Commandments which God had written on two tables of stone, but the civil law which Moses had written in a book—the law of Moses], when they were finished, that Moses commanded the Levites, who bore the ark of the covenant of the LORD, saying: "Take this Book of the Law, and put it beside the ark of the covenant of the LORD your God, that it may be there as a witness against you. "
Notice that the Book of the Law was not placed inside the ark, but "beside" (by the side of, RSV) the ark. This is why the Book of the Law is not mentioned in I Kings 8:9 as being in the ark. The Book of the Law, along with the pot of manna (Exodus 16:33-34) and Aaron's rod, was kept beside the ark, not in it. All of these items could properly be described as being hou—in the same place as—the ark.