Where else is the phrase "hard service" found in the Bible, and what is made clear to us by the use of these words?
Isaiah 14:3–4 (ESV)
3When the LORD has given you rest from your pain and turmoil and the hard service with which you were made to serve,
This is an expression that does not often occur in the Bible but was also used to describe the oppression under the Egyptians. God would free the Israelites in the same way.
3 When the LORD has given you rest from your pain and turmoil and the hard service with which you were made to serve,