Genesis 49:15

And he saw that rest was good, and the land that it was pleasant; and bowed his shoulder to bear, and became a servant unto tribute.

Cross-references

Genesis 30:18 gives Issachar's name meaning 'wages' — later the tribe becomes a servant for hire, fulfilling that meaning.

Psalm 81:6 says God removed the burden from Israel's shoulder — directly contrasting Issachar voluntarily shouldering a burden.

Matthew 23:4 shows Pharisees laying heavy burdens on people's shoulders — a contrast to Issachar's self-imposed servitude.