The first occurrence.
And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so. Gen 1:7
(In the Scripture Picture: Therefore a man shall leave his father …)
The primitive root.
kaph כ ך = the open palm, thus bend, open, allow, tame
vav ו = the tent peg, thus add, secure, hook
nun נ ן = the seed, thus continue, heir, son
The story: The opening (kaph) of the seed (nun); i.e., the going down of the root, which secures (vav) or establishes the plant — it is the thing which allows it to stand upright. That the vav, meaning security, is at the heart of the word, provides a further picture of that which firmly establishes coming from the core, or heart.