Ruach hakodesh is reason Biblical verses are omnisignificant - Netziv

Netziv(Kadmos HaEmek – She’iltos 2:2 -3): When there is some irregularity in the way a Torah verse was written, we find that our Sages often inferred information (derash) both for the subject of the verse and unrelated matters…. And surely this is true for Agada, mussar and ethical lessons – even when there is no obvious connection to the verses. Not only is this true for Torah but also for Biblical verses in Prophets and Writings which were put in writing through prophecy or ruach hakodesh. They are interpreted (drash) both according to the context and not according to the context. According to the context that means when the verse can be understood in a variety of ways. To say that all ways are true is an inherent property of something written with ruach hakodesh. An example of saying that interpretations which are not according to the context are also included in the verse is that of Rabbi Akiva who asks how do we know that a ship is spiritually pure? He answers from Mishlei(30:19),  “The manner of a ship in the midst of the ocean.” He says just as the sea is spiritually pure so is the ship. ...  And similarly we find with the words of Agada concerning the Shunamite woman and Elisha (Berachos 10b) that one who provides hospitality to a talmid chachom in his home is as if he brought a Tamid sacrifice. It  is clear that the Shunamite woman had no thoughts about a Tamid sacrifice when she provided hospitality to Elisha. What was asserted in the gemora is based on the idea that the words of a prophet can be broadly interpreted. This understanding of the Biblical verses is like a hammer striking a rock which sends out sparks both in its place and out of its place – to places where the one striking the rock never imagined they would fall. In a similar manner the verse alludes to many issued and principles even regarding matters which are not related to the verse at all. .

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To get a greater context of omnisignificance see the following article [fixed link]

Dr. Elman - Rebirth of Omnisignificant Biblical Exegesis