In Isaiah 56:2, the blessing is on those who keep the Sabbath; here eunuchs are specifically commended for the same practice — a direct internal parallel.

Isaiah 55:3 describes the everlasting covenant of steadfast love that eunuchs are called to hold fast in 56:4.

2 Samuel 23:5 refers to the everlasting covenant with David that eunuchs hold fast in 56:4.

Jeremiah 50:5 speaks of joining the Lord in an everlasting covenant, echoing the covenant eunuchs hold fast in 56:4.

Genesis 17:9 commands Abraham to keep God's covenant, a charge echoed for eunuchs in 56:4.

Exodus 19:5 promises that keeping the covenant makes Israel God's treasured possession, similar to the promise for eunuchs in 56:4.

Exodus 20:8 gives the Sabbath command that eunuchs in 56:4 are keeping.

Leviticus 19:3 commands Sabbath observance, which eunuchs are fulfilling in 56:4.

Deuteronomy 23:1 excludes eunuchs from the assembly, but Isaiah 56:4 promises blessing to those who keep God's covenant.

Deuteronomy 29:9 urges Israel to keep the covenant, a charge echoed for eunuchs in 56:4.

Matthew 19:12 mentions eunuchs for the kingdom; this verse promises blessing to eunuchs who keep God's covenant — a clear thematic link on eunuchs.

Deuteronomy 30:19 presents the choice between life and death; here eunuchs choose what pleases God — a specific application of choosing life.

Joshua 24:15 calls for choosing whom to serve — this parallels the eunuchs' choice to please God in Isaiah 56:4.