Hebrews 5:3

3 This is why he has to offer sacrifices for his own sins, as well as for the sins of the people.

Read Hebrews 5:3 Using Other Translations

And by reason hereof he ought, as for the people, so also for himself, to offer for sins.
Because of this he is obligated to offer sacrifice for his own sins just as he does for those of the people.
That is why he must offer sacrifices for his own sins as well as theirs.