Matthew 5:36

And do not swear by your head, for you cannot make one hair white or black.

Matthew 6:27

Which of you by being over-anxious can add a single foot to his height?

Matthew 23:16-21

"Alas for you, you blind guides, who say, "'Whoever swears by the Sanctuary it is nothing; but whoever swears by the gold of the Sanctuary, is bound by the oath.'

Luke 12:25

And which of you is able by anxious thought to add a moment to his life?

Treasury of Scripture Knowledge

Summary

Neither shalt thou swear by thy head, because thou canst not make one hair white or black.

General references

Bible References

Shalt

Matthew 23:16
"Alas for you, you blind guides, who say, "'Whoever swears by the Sanctuary it is nothing; but whoever swears by the gold of the Sanctuary, is bound by the oath.'

Because

Matthew 6:27
Which of you by being over-anxious can add a single foot to his height?
Luke 12:25
And which of you is able by anxious thought to add a moment to his life?

General references

Luke 12:25
And which of you is able by anxious thought to add a moment to his life?