The LORD
Yhovah (yeh-ho-vaw')
(the) self-Existent or Eternal; Jehovah, Jewish national name of God -- Jehovah, the Lord.
knoweth
yada` (yaw-dah')
to know (properly, to ascertain by seeing); used in a great variety of senses, figuratively, literally, euphemistically and inferentially
the thoughts
machashabah (makh-ash-aw-baw')
cunning (work), curious work, device(-sed), imagination, invented, means, purpose, thought.
of man
'adam (aw-dawm')
ruddy i.e. a human being (an individual or the species, mankind, etc.) -- another, + hypocrite, + common sort, low, man (mean, of low degree), person.
that they are vanity
hebel (heh'bel)
emptiness or vanity; figuratively, something transitory and unsatisfactory; often used as an adverb -- altogether, vain, vanity.