What's the benefit of chanting the mantra Abracadabra?

Answers from the books of Samael Aun Weor

The Thymus gland regulates the vitality of the children. Astrologists say that this gland is influenced by the moon. The Gnostic wise men want to look after the Thymus gland, and not let it get into decrepitude. When this gland is active the organism doesn't age. The ancient wise doctors used to say that the Vowel "A" when is wisely pronounced it has the power to make vibrate the Thymus gland.

The old doctors from ancient times used that wise Mantra so popularized by the people, called ABRACADABRA apparently to keep active the Thymus gland during all the lifelong.

Samael Aun Weor. Fundamental Notions of Endocrinology and Criminology.