Why does the author of Hebrews interchange heart and mind in Hebrews 8 and 10?

Question

In one instance the author of the book of Hebrews says he will write the laws in their hearts and put them in their minds

Hebrews 8:10 ESV

For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my laws into their minds, and write them on their hearts, and I will be their God,

But later changes and says he will write them in their minds and put them in their hearts

Hebrews 10:16 ESV

“This is the covenant that I will make with them after those days, declares the Lord: I will put my laws on their hearts, and write them on their minds,”

Was this a deliberate word play, style of writing or something else?

Answer 1

The original verse of Jer 31:33, to which both Heb 8:10 and 10:16 allude says this:

• LXX text: For this is my covenant which I will make with the house of Israel; after those days, saith the Lord, I will surely put my laws into their mind, and write them on their hearts; and I will be to them a God, and they shall be to me a people.
• Hebrew: “But this is the covenant I will make with the house of Israel after those days, declares the LORD. I will put My law in their minds [ קֶרֶב ] and inscribe it on their hearts [ לֵב ]. And I will be their God, and they will be My people.

The precise meaning of the two Hebrew words (respectively) used above is this:

• קֶרֶב = inward part, midst
• לֵב = inner man, mind, will, heart

Note that both could be translated as "mind" or "heart" because both are part of the "inner man". However, the LXX is quite unambiguous.

Therefore, when Hebrew quotes Jer 31:33, both Heb 8:10 and 10:16 are "possible" translations of the Hebrew.

Answer 2

Dottard's answer is definitive. Here, I'll supplement a little.

NET Bible, Jeremiah 31:

33 "But I will make a new covenant with the whole nation of Israel after I plant them back in the land," says the LORD. "I will put my law within them [H7130] and write it on their hearts and minds [H3820]. I will be their God and they will be my people.

Strong's Concordance:

H7130 קֶרֶב qereb: inward part, midst

H3820 לֵב leb: inner man, mind, will, heart

NET:

I will put my law             within them               
and write it                  on their hearts and minds

H3820 is particularly polysemantic and there was no exact Greek equivalent. As the Greek language did not have the equivalences of H7130 and H3820. LXX interpreted these words as G1271 and G2588 which appear in Brenton Septuagint Translation as:

I will surely put my laws     into their mind, 
and write them                on their hearts

Now fast-forward to the Hebrews writer, it seems that he knew the OT language but wrote in Greek and decided to write Hebrews 8:10b as:

 I will put my laws          into their minds, 
 and write them              on their hearts

Then did a switcheroo in Hebrews 10:16:

 I will put my laws          on their hearts, 
 and write them              on their minds,

Was this a deliberate word play, style of writing or something else?

I think this is a piece of evidence that the Hebrews writer knew the biblical Hebrew language and deliberately decided to do a switcheroo to reflect the parallelism and polysemy of H7130 and H3820.