Genesis 37:31

And they took Joseph’s coat, and killed a kid of the goats, and dipped the coat in the blood;

Cross-references

Genesis 37:3 describes Joseph's special ornamented robe — the very robe the brothers now dip in blood to deceive Jacob.

Genesis 37:23 records the brothers stripping Joseph of his robe — the same robe they now use in their deception of Jacob.