An interesting crossover with another recent thread discussing Micah 6:8 and the word 'chesed'. Verses 6-7 describe the potential offerings to be made to Yahweh. Included is his firstborn son.
With what shall I come before the Lord
and bow down before the exalted God?
Shall I come before him with burnt offerings,
with calves a year old?7 Will the Lord be pleased with thousands of rams,
with ten thousand rivers of olive oil?
Shall I offer my firstborn for my transgression,
the fruit of my body for the sin of my soul?8 He has shown you, O mortal, what is good.
And what does the Lord require of you?
To act justly and to love mercy
and to walk humbly[a] with your God.
Here the writer at least makes acknowledgement of the idea of sacrificing the firstborn. Dating the work is notoriously difficult. It may retain elements from an 8th century prophet, however if so, the failed predictions were revived and reworked during the 6th/5th century. So, while the author of the passage above seems, like Ezekiel and other prophets, to disparage the idea of making sacrifices in favor of acts of loyalty/kindness, the mention of the sacrifice of the firstborn as a sin offering betrays the historical realities.