The three Mâtrâs (A+U+M), if employed separate, and only joined one to another, are mortal; but in acts, external, internal, or intermediate, if well performed, the sage trembles not.

In plain words: The three sounds of Om, used separately, lead only to things that pass away. But when they are joined and used rightly in every kind of action, outer, inner or in between, the wise person does not shake with fear.