A good professional explains when another person is better suited to the task.

Turning work away costs money and buys something that cannot be bought any other way. A person who tells you this is not their strength has told you, in the same breath, that the things they do take on are genuinely theirs. Everyone can sense the difference between an expert and someone competing for every job.

The next time something falls slightly outside what you do well, say so and name someone better. You lose one piece of work and gain a person who now trusts your yes. If you are hiring, listen for that honesty, and be more careful with anyone who is equally confident about everything.