According to Quintilian, the art of the first- century orator influenced the written style of language
The Institutio Oratoria 10.3.5
Karen H. Jobes argues “that what is typically perceived in Heb 10:5–7 as a ‘misquote’ of the psalm from which the writer of Hebrews must somehow be absolved, is instead his deliberate use of a phonetically based rhetorical technique called paronomasia which was highly valued in the first century.”
Basically, Jobes says that oral and written transmission of information means the perceived misquotes of the Hebrews source material aren’t simply misquotes based on textual criticism. They are deliberate choices made by the author to serve an audience who may hear the work being read to them.
Hebrews 10:5-7
Masoretic Text, Psalm 40:7-8
Septuagint, Psalm 39:7-8
Jobes again:
This “misquote” of Psalm 40 in Hebrews 10 should caution modern readers not to impose twentieth-century standards of precision and accuracy on first-century quotations of the OT. First-century authors apparently were not motivated by the precision and accuracy demanded in quoting sources today but were conforming to different standards which may seem strange to the modern reader.
The Function of Paronomasia in Hebrews 10:5-7, Karen H. Jobes
This has implications on the view of inspiration. If God were directly transmitting the words to the author, so to speak, while the author wrote them down, God would certainly not have misquoted the intended passage. If God’s providence prepared the Hebrews writer with his life experience, understanding of language, education, cultural context, etc., the writer can then use his or her own rhetorical expertise to pen the work. God’s providence ensured the author would get it right.