Leviticus 8:24

And he brought Aaron’s sons, and Moses put of the blood upon the tip of their right ear, and upon the thumbs of their right hands, and upon the great toes of their right feet: and Moses sprinkled the blood upon the altar round about.

Cross-reference

Leviticus 14:14 uses the identical blood application on ear, thumb, and toe for cleansing a leper — mirroring this ordination rite.

Exodus 29:20 gives the same instructions for applying blood to ear, thumb, and toe — this is the parallel account of the ordination.