And Moses said to Aaron, “Take a jar, and put an omer of manna in it, and place it before YHWH to be kept throughout your generations.”
Exodus 16:33 #beshalach

The manna gathered by the people perished after a day, while the manna gathered by Aaron lasted forever. This is a picture of man's doctrines and traditions--even those based on Scripture--opposed to God's. Man's efforts at understanding God's will are always flawed and become corrupted with time, but that isn't a reflection of God's actual words, which are eternal and incorruptible.