Hebrews 7:13

For he of whom these things are spoken pertaineth to another tribe, of which no man gave attendance at the altar.

Cross-references

Numbers 16:40 reinforces the restriction that only Aaron's descendants could serve at the altar, supporting Hebrews' point that no one from Jesus' tribe (Judah) served.

2 Chronicles 26:16-21 gives the example of King Uzziah from Judah attempting priestly service and being punished, illustrating the prohibition Hebrews mentions.