What was in the Ark of the Covenant? Hebrews 9:4 reads, “the ark of the covenant covered on all sides with gold, in which was a golden urn holding the manna, and Aaron’s staff that budded, and the tablets of the covenant” (all Scripture ESV). Here, the author of Hebrews lists three items that were “in” the Ark: a golden urn holding manna, Aaron the high priest’s staff and the tablets of the 10 Commandments.
It seems so straightforward. But curiously enough, the Old Testament only lists one of these three items that were placed within the Ark. In Exodus, after giving Moses the 10 Commandments (and the rest of the Law), God commands Moses, “And you shall put into the ark the testimony that I shall give you” (Exod 25:16; cf. vs 21). The tablets containing the Law were to be placed within the Ark of the Covenant. Deuteronomy 10:1-2 confirms this commandment of God.
1 Kings 8:9 indicates that—at least during the time of Solomon—“There was nothing in the ark except the two tablets of stone that Moses put there.” 2 Chronicles 5:10 confirms this statement with a parallel text.
So where did the manna and staff of Aaron come in?
Both are mentioned in the Old Testament as items to be placed in front of the Ark. Right after the manna falls from Heaven, God commands Aaron through Moses, saying, “Take a jar, and put an omer of manna in it, and place it before the LORD to be kept throughout your generations” (Exod 16:33). As God commanded, so Aaron did (vs 34). The Hebrew is clear that the jar of manna was placed “before/in front of” the Ark, not “in” it, which would have required a very different Hebrew word.
The same goes for Aaron’s staff. After the staff buds with almond blossoms, the Lord says to Moses, “Put back the staff of Aaron before the testimony, to be kept as a sign for the rebels, that you may make an end of their grumblings against me, lest they die” (Num 17:10). Again, the word “before” indicates that the rod should not be placed in the Ark, but in front of it.
So let’s examine the evidence:
1) God clearly commanded Moses to place the tablets of the 10 Commandments into the Ark of the Covenant.
2) God clearly commanded Moses and Aaron to place the jar of manna and the budding rod of Aaron in front of the Ark.
3) At the time of King Solomon, the Ark contained only the two tablets, not the other elements.
4) The author of Hebrews understood the Ark to contain not only the tablets, but also the manna and staff.
Unfortunately, the Bible gives us no other data that is useful to fill in this rather large gap. The most we can say is that sometime between the time of King Solomon (970-931 BC) and the time of Hebrews (just before 70 AD), the Israelites saw it fit to place the additional objects within the Ark of the Covenant. Why and when and who did it, we do not know. But if we take the Bible as God’s inspired word which does not contradict itself (which I do), then this is the most we can say without resorting to other outside historical sources (which do not help us very much, either).