Ramban (Toras HaShem Temima) And when we take a good look, we see that a person has no part in the Torah of Moses until he believes that all our words and actions are miracles there is no worldly nature in them. That is because the essence of the Torah is complete miracles and wonders, because there is no difference for those who take a good look between a righteous man who lived eighty years quietly and safely and without illness, ... and between the splitting of the Red Sea. …The general rule is everything in the Torah are either miracles or potential miracles and that is why G-d specifies them in the Torah. ..For example, , no man knew that the deliverance of so-and-so from an illness was from charity he gave, and the death of a healthy person was due to eating prohibited fat, but both are equivalent. That is why astonishment was expressed regarding the Rambam because he is always minimizing miracles and emphasizing the natural. He also claimed that miracles are only temporary aberrations when in fact they are permanent – as he himself admitted in his Letter on Resurrection of the Dead.
Rabbeinu Bachya (Shemos 30:12) In fact it is axiomatic to remember that a person is not a true believer, i.e. does not really have a share in Moses’ Torah unless he is absolutely convinced of the fact that G-d performs such hidden miracles all the time, that there is no accident and no coincidence in the universe. G-d is aware of all that occurs and has had a hand in it
Sefer HaChinuch (132) The thing is known amongst us and among every sage that the great miracles that God does for people in His great goodness, He always does hiddenly. And these matters appear a little as if they were truly done by way of nature, or close to nature.